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Discussion Starter · #1 · (Edited)
Seems the TD04 guys have all the support and easy numbering system from 13T to 19T. The factory Saab TD04-15T starts off with a 300hp ceiling (at the crank), making it more desirable right off the bat with a simple turbo swap.

Well, what about the T25 (GT2554 is it's technical name) guys who want something different, or want more than a 300 hp offering and don't want to buy a TD04 and then spend money upgrading that? You're in luck as there are available Garrett wheels that can fit the shaft of the GT25 series turbo.

A GT25 series turbo means the exhaust wheel has a 53mm turbine wheel. A GT28 series has a 53.90mm turbine wheel (some literature states it's a 53.85). The GT28 series will spool a little later and is typically designed for slightly larger displacement engines, though it can work with 2.0L - 2.3L. It is possible to outfit this larger turbine into a T25, though definitely not necessary. Also, the "T25" is a journal bearing turbo, whereas most of the newer Garrett stuff is ball bearing. An "R" at the end of the model number designates the ball bearing CHRA. A compressor wheel from a ball bearing unit will fit a journal bearing as well as the turbine wheel and shaft are interchangeable ;ol;

There really isn't a hp difference (as stated by Garrett's own literature) between the GT25xx and it's GT28xx counterpart assuming the exact same compressor wheel is in use and we're NOT including GTX Garretts. So, a GT2554 and a GT2854 WILL produce the exact same overall theoretical 270hp. http://www.turbobygarrett.com/turbobygarrett/turbocharger There's always exceptions to the rules like ported housings, different A/R, etc. but I'm not going into that as it's irrelevant to this post and doesn't overly change HP numbers. HP figures are near MAX hp available for the given wheel. I believe Garrett uses different PSI from the waste gate to alter the numbers and make certain models artificially low?

Available compressor wheels to fit a "T25" are:

59mm 56 trim
HP 310 at the crank

60mm 60 trim as found on a "real" GT2560R (old GT28R)
HP 330 at the crank

60mm 62 trim as found in GT2860RS and it's variants
HP 360 at the crank

63mm 56 trim
HP 430* (This is found in the GTX sub line which lists unusually higher HP numbers)

67mm 55 trim
HP 480* (This is found in the GTX sub line which lists unusually higher HP numbers)

71mm 52 trim (This might be too big as the adapter ring for the compressor housing might need machined?)
HP 475 at the crank


As you can see, there is a variety of compressor wheels that are available with healthy HP numbers. The stock T25 compressor housing can be ported to accept up to a 60mm wheel. Anything larger will need a GT28 series compressor housing. Places such as ATP turbo not only sell the proper housing to fit most of these wheels, they also sell an adapter ring (don't forget the hardware kit for it) that allows you to run the larger comp housing ON a T25 CHRA. If needed, buy a GT2860RS comp housing and have it machined for the larger sizes. If you go this route, you'll need to make room to get it to fit in the stock location. I had to grind the block, grind top of the housing, run 2 gaskets, remove AC. and cut a portion of the AC bracket to get a GT28 comp housing to fit the stock location w/o a spacer. I suggest a 2 bolt inlet for clearance issues and recommend buy a spacer to move the turbo to make it fit easier.

The GTX turbos make a ton more HP than there non GTX counterpart. I have no idea why other than Garrett might have higher PSI pre-configured through the waste gate or possible the housings are more efficient?

I wouldn't recommend a 76mm (it's too big and might be too heavy). A 71mm will *fit*, though you'll have to remove a wide area of material to get it in the recess of the CHRA (superback) and it might be really close to the adapter ring. I'm willing to try a 71mm (that 67mm might be a better alternative :cheesy:) at some point (money and time permitting) with my spare T25 and see what happens.

Always DOUBLE CHECK and do your homework before attempting to fit any other wheels. Anything larger than the 60mm 62 trim- you might very well be the 1st to try it ;) and I have no idea how that will go, so try at your own risk. I'm simply stating that they'll fit. HP numbers should be very close to Garrett's stated numbers (no idea with the GTX ones). You MUST port (or get an aftermarket turbine housing) your turbine housing's runner to get it flowing more and keep EGT at bay (it does make a difference ;ol;). A 9000 T25 housing as a wider (oval) inlet but the throat ports the same as a 9-3 housing with the smaller (round) inlet. You're also going to want a 360 degree thrust plate in there to help keep lateral loads in check and better use new bearings and seals. And above all else, get it balanced! If you embark on one of the wheels listed, please post your results. You can upgrade a functioning T25 for $300-500 with a new wheel, comp. housing and adapter ring, 360 kit, rebuild kit, & balance. Gpop has good balance rates, but watch they don't overcharge for shipping back to you!!
 

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The GTX turbos make a ton more HP than there non GTX counterpart. I have no idea why other than Garrett might have higher PSI pre-configured through the waste gate or possible the housings are more efficient?
GTX turbo's have completely different compressor wheel designs. They are forged billet Aluminum alloy versus cast wheels you see on most other turbos. They are much more efficient but there is one major downer, they make quite a bit less spooling noise.
 

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The OP left out in the post about how already-high stock EGT's are going to sky rocket without a larger turbine housing. "I'm going to upgrade my exhaust housing so I can have more lag," said nobody ever. The whole reason for doing so is to allow more flow potential with the obvious side effect of there being less back pressure and lower exhaust temperatures. There is such a thing as the compressor and exhaust wheel being mismatched and this is definitely one of those cases.

Do not upgrade the T25 much beyond a T28. You'll just be asking to grenade your turbo and you'll be lucky if there's not more severe damage accompanied with that.

Still not sure why the OP is so against the TD04 and would instead rather keep throwing money at the stock turbo.
 

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Discussion Starter · #4 ·
GTX turbo's have completely different compressor wheel designs. They are forged billet Aluminum alloy versus cast wheels you see on most other turbos. They are much more efficient but there is one major downer, they make quite a bit less spooling noise.
I read they were billet. Could be they are more delicate and need a better process? Being quieter is definitely a downer, but if a 67mm can be made to fit a GT28 housing and bring anything near that power level, I say what the hell? Not to mention, the price tag would be *much* cheaper than the real deal. Right now ATP turbo is selling the GT2860RS housing for $130. I think it was $160 when I bought mine. There's a lot of room in that housing to fit a bigger wheel. I think the 2876 uses a ported out version of it, I know the 71mm will fit it. Port it and run (assuming it fits) the 63mm or that 67mm GTX wheel and you're saving over a grand for the real thing. ATP wants $1400 for the GTX2863R and GTX2867R and neither even come with the exhaust housing which is probably another $400-500.

It should go without saying, but you GT28xx guys can upgrade to the same options plus the 71mm and 76mm wheels are a possibility.
 

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Discussion Starter · #5 ·
You MUST port (or get an aftermarket turbine housing) your turbine housing's runner to get it flowing more and keep EGT at bay (it does make a difference ;ol;).
Was brought to my attention a hateful member posted something without even reading the entire post. Not even worth defending the rest as it's all opinion designed to troll and illicit a negative response.


Time to go put on my duck boots and walk in the rain.....
 

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I'm confused man. While his post was a bit sharp his point is definitely legitimate. It is a very good idea to run a bigger a/r or clip the turbine wheel. When you talk about 60mm+ compressors you could have egt issues with the tiny stock turbine housing and turbine.
 

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Discussion Starter · #7 ·
I'm confused man. While his post was a bit sharp his point is definitely legitimate. It is a very good idea to run a bigger a/r or clip the turbine wheel. When you talk about 60mm+ compressors you could have egt issues with the tiny stock turbine housing and turbine.

Confused at me? Thought that was covered with getting a different exhaust housing or porting it for more flow. Unported, they're very restrictive and I wouldn't even run the 53.90 in it w/o having it ported. I've covered porting it pretty extensively. NA, the car frees up at least 15 hp. Some you tube video of before/after with only the exhaust and trying to climb a hill. Pretty significant difference. Running that ported housing with turbo in my sig I was getting 6 sec 0-60 with no tune, skinny factory tires, and a shot suspension. The main point I'm trying to get out is you have options with a "T25" CHRA. That guy just doesn't like me.
 

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Discussion Starter · #8 ·
Looking at some TD04 exhaust side numbers, they don't seem to be really that much different than a GT25 series turbo?


6 cm^2 = 0.41 A/R.
---------------------- VS .48 A/R GT25
7 cm^2 = 0.49 A/R
 

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While A/R is calculated the same for all turbine housings I don't believe you can compare turbine flow at all with between different turbines using just A/R. Even if the inducer of the turbine was the same, the pitch of the blades, blade count, exducer/inducer ratio(trim) all have an effect on flow.
So in this case I don't know if the TD04HL and the T25 A/R is an apples to apples comparison.
Here are a couple stats Ive tucked away over time as I thought about a bigt28 or other hybrid

T25 turbine
41.7 mm / 52.7 mm
11 blades

TD04HL
45.6 / 52 mm
12 blades
 

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While A/R is calculated the same for all turbine housings I don't believe you can compare turbine flow at all with between different turbines using just A/R. Even if the inducer of the turbine was the same, the pitch of the blades, blade count, exducer/inducer ratio(trim) all have an effect on flow.
So in this case I don't know if the TD04HL and the T25 A/R is an apples to apples comparison.
Here are a couple stats Ive tucked away over time as I thought about a bigt28 or other hybrid

T25 turbine
41.7 mm / 52.7 mm
11 blades

TD04HL
45.6 / 52 mm
12 blades
That's exactly right. And manufacturers spend plenty of time in R&D figuring out what combination of what works best.

Oh and just so you know this guy just thinks I hate him as if I'm upset that he's uncovered something special. I don't knock people for trying new things but when there's no real logic behind it, I can't help but say something. Believe me I try to be nothing but helpful, I've been on here for awhile and gotten a lot of advice and I'm only happy to share any legitimate information that I feel is worth passing on.
 

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Was brought to my attention a hateful member posted something without even reading the entire post. Not even worth defending the rest as it's all opinion designed to troll and illicit a negative response.


Time to go put on my duck boots and walk in the rain.....
See, he mentions porting here. But has he taken the time or spent the money to actually collect data and see what the EGT's really are? Or is trying to port what's already a tiny housing just going to automatically put EGT's at a safe level? I don't think so. I don't remember the exact numbers but EGT's on a stock TD04-15T with the 6cm^2 housing are already alarmingly high. I don't even want to know what they are on a T25. I had mine at stage 3 for two years and I beat the mess out of it, by the end just before the HX35 was ready to go on I would occasionally get smoke out the exhaust from the shot turbo bearings.

Again, this guy flat out doesn't know what he's talking about and he doesn't care to listen to what other members, who have been on this forum and have been playing with Saab's for just a teeny bit longer than him, have to say. Thus, any words against what he's saying is considered trolling and negativity. :nono;
 

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stock software with 3 inch turbo back on a 15t-5cm has been logged in the 1700F range in the manifold (925c). I believe there is a very old post around from Dr. Boost that had a lot of data and stated that something in the range of 950-980c was acceptable. these cars run oddly hot to begin with. unfortunately like i said previously, i have lost my notebook with years of saab data in one of my many moves.


but im sure pontius has no idea who dr. boost is/was anyway so he wont believe it.
 

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stock software with 3 inch turbo back on a 15t-5cm has been logged in the 1700F range in the manifold (925c). I believe there is a very old post around from Dr. Boost that had a lot of data and stated that something in the range of 950-980c was acceptable. these cars run oddly hot to begin with. unfortunately like i said previously, i have lost my notebook with years of saab data in one of my many moves.


but im sure pontius has no idea who dr. boost is/was anyway so he wont believe it.
That's funny, 1700F was what I thought my buddy Drew told me but didn't want to quote it cause I wasn't certain. I imagine pushing things from the software only raises the EGT's higher. I have NEVER seen 1700F on my car thankfully, I want to say that even when I ran the car up to 160mph they only climbed to somewhere in the 1600F range.

Ah, good point. Your post was pointless, go away saabkid.
 

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Discussion Starter · #14 ·
@ Saabkid I don't run a TD04 so why would I care what EGT's it has? Has nothing to do with the post either :roll:


Back on topic in regards to the GT2560:

I run these with the 3 bar map sensor and larger injectors and you can get over 300whp when its tuned right.

John
 

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@ Saabkid I don't run a TD04 so why would I care what EGT's it has? Has nothing to do with the post either :roll:


Back on topic in regards to the GT2560:
Well since you haven't been so kind as to go out to your car with your EGT gauge and gather some data from the almighty GTX25, data for the TD04 is the next best thing we have. Expect the numbers from it to be similar, probably worse.

Not sure what you proved by quoting that; yes, John has run plenty of T28's and made 300whp from them. If you think you're going to do the same then go ahead, I'll wait. I'm still waiting on any kind of data from you other than what you can pull from some brochures. I never said you won't make more than 240whp but so far I've seen nothing.
 

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To throw a couple more facts into the mix. The turbine wheel is not identical between the GT2556 and the GT2860RS. Here is a comparison of the two turbine maps. If you look at them you can see the sizable difference in flow even with the same A/R housing. I wish I had a TD04HL map to compare these to but I don't at this time.

My take is you can definitely upgrade the T25 to make decent power but with the same money required for the various upgrades you could purchase outright a more performance oriented turbo. If someone prefers the instant spool of a stock framed turbo to more HP at the top end, then more power to them. I am looking at something in the middle. Towards a GT30 which would be overkill for my desires but above my stock TD04.

 

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Ok, let's play along with this for a second and see what happens. Pon Pon wants to make 360bhp from his engine right off the line. Let's change it to whp for us, so *.88 = 317whp

Just to start, since there doesn't seem to be much understanding of how horsepower works, let's say he thinks he's going to make 317whp at 2000rpm because he wants something that's spooled as soon as he steps on the gas.

HP = (Torque*RPM)/5252 and so

317 = (T*2000)/5252, T=832lb.ft.

In order to be making 317whp at 2000rpm, only 832lb.ft. needs to be hitting the ground.

A. Yeah right.
B. I hope you're wearing your slicks. Useless much?



Ok so maybe he decides, "Alright, maybe that IS a little crazy I'm not going to make 360bhp right off the line. What about at 3000rpm?" Well...

317 = (T*3000)/5252, T=555lb.ft.

Hmm doesn't seem so plausible either. Moving on...

At 4000rpm: 416lb.ft.

Wow that's a lot! But is this little guy really going to make 416lb.ft. of torque at any point in it's rev band? Not before it grenades.

At 5000rpm: 332lb.ft.

Getting warmer..

6000rpm: 277lb.ft
7000rpm: 238lb.ft.



So, Pon Pon CAN make 360bhp from this turbo! Of course those first few torque values were absurd but if he can just wait til 6000rpm and make 277lb.ft. then he'll be golden!! But hold on a second..

Aren't these supposed to make power throughout the whole rev band? What happened?

My point is you're going to be busting your turbo's balls to get to what you're trying to do. That's why people go bigger and sacrifice some spool, not to mention there is no reason to have that much torque at 2000rpm. Tell me, what do you expect to do with even 350lb.ft. of torque at 2000rpm in a street car on street tires? Have you ever driven a front wheel drive car that makes that much torque? Much more than 400lb.ft. will break the tires loose on the highway, what in the world makes you think that it's gonna be more useful just as the car starts moving? Answer me that.


Next, you claim that you've got a more useable powerband with a small turbo because a small turbo 'holds the power til redline' . Hmm.
I googled and pulled a dyno chart of a Mazda Miata running this GT2560R that you speak of.



Reading it from left to right, torque climbs to max boost at 4200rpm then drops off consistently from there. Is your idea of a good time only running through one gear? Because if you follow that torque curve all the way through redline and then shift, do you not realize that you're going back down to that 4500rpm (give or take) area where torque might be it's highest but also where it starts to take a nose dive from there? Explain to me how that is holding the power til redline. Why do you think horsepower curves on smaller turbos also peak and then tank? BECAUSE THEY ARE NOT EFFICIENT WHEN PUSHED HARD.


I'm currentely daily driving a stage 2 STi on methanol while I get my car sorted back out. Let's look up a dyno for that.



This is pretty accurate (without meth) - 280whp and 325lb.ft. of torque. Just as the dyno shows, this car is a blast from a stop light. From a stop the car just takes off with no traction issues due to the AWD. As I approach the redline you can literally feel the power dropping off. Time to shift to second gear right back down to the area where the torque has already peaked and is only going down from there. If I decide to go all the way up to 100mph in the STi, how many times will I be facing 'turbo lag'? Just once: in first gear.

I don't know the source of your misguidance but having the torque come rushing at you all at once and as soon as possible is useless. I have spent countless hours driving my own car around trying to figure out what makes the car go faster. I've called on as much boost as possible as early as possible only to get wheelspin in 3rd gear (or 5th on E85). I then flattened my boost curve and made it ramp up with rpm from 5000rpm and on. On LESS boost (read:torque) I achieved the same acceleration numbers from 30-50, 30-60, 40-70 etc. as I did when I tried to go using ridiculous amounts of torque. Best of all, I'm not worried for my turbo's life throughout any of this because I know I'm barely pushing it and that I have room to grow if needed. I've also NEVER broken a transmission whereas you'll see people on here running stage 3-5 cars doing it all the time.

So when you sit there and try to tell us that your car is faster than any car with a Holset on it from a stop just because it spools quicker, you better believe I'm going to stop you in your tracks because I've spent the time out on the road with a laptop in front of me doing pull after pull and I've stuck my car on a dyno twice to verify everything I've learned.

Stop getting butt hurt when it seems like nobody on here is agreeing with what you're saying. There's a reason for it. I worked at a middle school for years and I would have kids come tell me all the time that one of their teachers just hates them for no reason and you're acting just like that :roll: nobody on here hates you, it's not like I don't want you to make more power on your car. I frankly don't care. If you want to shut us all up though since you think we're just giving you a hard time for the hell of it, disprove everything I've said. Show me that you can make whatever power you're gonna make at a SAFE EGT level and at a normal amount of boost. If you eek out 300whp at 2000F exhaust gas temperatures running 40lbs of boost on that sucker then you've proven my point. Prove me wrong and I'll go check into psych ward because the laws of physics have obviously changed then.
 

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Discussion Starter · #19 ·
Well since you haven't been so kind as to go out to your car with your EGT gauge and gather some data from the almighty GTX25, data for the TD04 is the next best thing we have. Expect the numbers from it to be similar, probably worse.

Not sure what you proved by quoting that; yes, John has run plenty of T28's and made 300whp from them. If you think you're going to do the same then go ahead, I'll wait. I'm still waiting on any kind of data from you other than what you can pull from some brochures. I never said you won't make more than 240whp but so far I've seen nothing.
Bud, I'm not sure what your deal is and frankly I don't care. I have a $950 winter car turned daily driver after I was forced to sell my Mark VIII after BWC went 6 months w/o paying me compensation for my back injury. I don't answer to you, I don't know you, and after the childish posts and antagonistic comments and following me from one thread to another to ?? is not going to get my respect. If you were respectful and not constantly contradicting yourself in an effort to I dunno, maybe you think you're cool for flogging me? Maybe I'd even give you the time of day. I think it's pathetic and a pitiful cry for attention. Also, a "T28" isn't even a turbo anymore. A GT28R (I'm assuming that's what you are referring to) is a 60mm 60 trim which is smaller than what I run. You should get in the habit of calling them by their current number designation so people know what you are even talking about as old "GT28R" doesn't even carry the 53.90 wheel found in a true GT28xx series turbo.

Porting a stock 9-3 or 9000 T25 housing does help it breath much better. I did back to back before/after in-car on the road tests and the "after" results were very significant. I don't need a pyro meter to tell me that. Garrett's site shows a GT2554 as 270 hp (Same as a T25 which oddly enough is a 270hp turbo). Well, that's the hp that turbo puts out. A GT2554 and a GT2854 make the EXACT same hp figures going off Garrett's numbers. Even the engine size recommendations are the same. So, I'm going to say a GT2560 (62trim) will make the same hp figures as a GT2860 (62 trim). Maybe it'll be off a few hp, maybe not, I personally don't care. It's a fun turbo and smokes the little thing it replaced. Is the 53.90 (GT28) wheel a more efficient design? Yup. I didn't run one because I like early boost and early higher hp/tq figures since that makes for a more fun street car to me and I didn't see the need of buying it and messing with a different housing, and since I have a GT2860 comp housing with the port work on the exhaust housing, I'm definitely doing better than a hybrid running both stock housing with no work done to them. If you can't respect any of this, that's on you. I've had you blocked for over a year and one would think you would have either moved on or matured by now, but unfortunately that's not the case.

Here's some old footage of the before/after porting with my old 9-3 T25 turbine housing which clearly shows a significant improvement when the car was running NA with a block-off plate covering the CHRA hole, so the test results are much easier to see and the only changes before/after are the porting. I've switched to a 9000 T25 housing and ported that the same way. Other than the wider oval opening, performance is slightly better.



Now, I'm done talking to you.
 

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Bud, I'm not sure what your deal is and frankly I don't care. I have a $950 winter car turned daily driver after I was forced to sell my Mark VIII after BWC went 6 months w/o paying me compensation for my back injury. I don't answer to you, I don't know you, and after the childish posts and antagonistic comments and following me from one thread to another to ?? is not going to get my respect. If you were respectful and not constantly contradicting yourself in an effort to I dunno, maybe you think you're cool for flogging me? Maybe I'd even give you the time of day. I think it's pathetic and a pitiful cry for attention. Also, a "T28" isn't even a turbo anymore. A GT28R (I'm assuming that's what you are referring to) is a 60mm 60 trim which is smaller than what I run. You should get in the habit of calling them by their current number designation so people know what you are even talking about as old "GT28R" doesn't even carry the 53.90 wheel found in a true GT28xx series turbo.

Porting a stock 9-3 or 9000 T25 housing does help it breath much better. I did back to back before/after in-car on the road tests and the "after" results were very significant. I don't need a pyro meter to tell me that. Garrett's site shows a GT2554 as 270 hp (Same as a T25 which oddly enough is a 270hp turbo). Well, that's the hp that turbo puts out. A GT2554 and a GT2854 make the EXACT same hp figures going off Garrett's numbers. Even the engine size recommendations are the same. So, I'm going to say a GT2560 (62trim) will make the same hp figures as a GT2860 (62 trim). Maybe it'll be off a few hp, maybe not, I personally don't care. It's a fun turbo and smokes the little thing it replaced. Is the 53.90 (GT28) wheel a more efficient design? Yup. I didn't run one because I like early boost and early higher hp/tq figures since that makes for a more fun street car to me and I didn't see the need of buying it and messing with a different housing, and since I have a GT2860 comp housing with the port work on the exhaust housing, I'm definitely doing better than a hybrid running both stock housing with no work done to them. If you can't respect any of this, that's on you. I've had you blocked for over a year and one would think you would have either moved on or matured by now, but unfortunately that's not the case.

Here's some old footage of the before/after porting with my old 9-3 T25 turbine housing which clearly shows a significant improvement when the car was running NA with a block-off plate covering the CHRA hole, so the test results are much easier to see and the only changes before/after are the porting. I've switched to a 9000 T25 housing and ported that the same way. Other than the wider oval opening, performance is slightly better.

T25 exhaust housing pre-porting - YouTube

T25 Exhaust Housing "After" Porting - YouTube

Now, I'm done talking to you.
Thanks for the unnecessary background. I missed the part in my post where I said, "please give me your respect." Plus you may notice that I'm nice to everyone else who doesn't lack common sense.

lol oh, we don't call them T28's? That's funny. Search the forum for T28 then search the forum for GT28 and tell me which one you find more references to. Once again, regurgitating the brochures rather than playing in real life.

Look I'll be honest, I didn't bother reading the rest of your post once I saw that you posted those videos again. I guess if you know it all because that's what the seat of your pants tells you then there's just not much hope for you anyway. I just didn't know you had a thermometer coming out down there too that told you how hot the exhaust temperatures were.
 
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