SaabCentral Forums banner

1 - 13 of 13 Posts

·
Registered
Joined
·
114 Posts
Discussion Starter #1
My local exhaust shop expert, although not familiar with Saab 900 Turbos,reckons that fitting a 3" exhaust in place of my existing 2.5" stock system will inevitably make it noisier (something I don't really want). My existing system is already a freeflow muffler with no cat so I wonder if changing it is really worth it. This leads me to ask two questions:
1. Have you guys found after fitting your 3" exhaust that it is considerably noisier? I don't mind the thought of a little extra noise,especially if it gives it a Ferrari sound :roll: but considerably noisier would just be a nuisance really.
2. Do you get a noticeable performance improvement or is it just one of those things you do along the way that helps other improvements work better?

Thanks!
 

·
Registered
Joined
·
948 Posts
From a performance standpoint, replacing the downpipe and cast elbow should free up a few horses and compliments other mods but after the downpipe there wont be much difference in performance between a 2.5 and 3" (if any)

The 3" is generally louder depending on your muffler/cat setup.
Will it sound more like a ferrari?...Not a chance.

I have a full 3" system (stock elbow), no cat, and a flowmaster 60 series muffler. Its a bit to noisy on idle (convertible) but it doesnt get exponentially worse as revs increase.
 

·
Registered
Joined
·
173 Posts
Could you post a sound clip of it? I'm trying to decide what to do about my exhaust and want something throaty, but I dont know what to buy without running the risk of sounding like a ricer.
 

·
Banned
Joined
·
5,841 Posts
This is very simplistic but the larger the bore the less resistance the gas in the exhaust has, (back pressure)

The exhaust gas tends to stack up after the turbine as its swirls and eddys around, its important for raw power and spooling speed to have as little resistance in this first two feet of exhaust.

The cast elbow drops the gas velocity which converts into more resistance.

A video clip of a full 3 inch system with a single back box.

When it drives off you can hear it well.
 

·
Registered
Joined
·
181 Posts
I've just fitted a full 3" system with the swan-neck downpipe in place of the existing standard system which had, at some point, had the cat removed and replaced with a straight pipe. Without the cat, the 3" system is slightly louder at tickover (makes a lovely burbling noise) but is a lot quieter at 2000-ish rpm.

I think the JT centre box is a lot more efficient than the original Saab item as it's very surprising how much gas comes out of the tailpipe at tickover
 

·
Registered
Joined
·
4,222 Posts
I have the full JT from the standard cast elbow back. It's louder, but not unpleasant or anti-social when just cruising around. When you stand on the loud pedal is increases in volume to a loud roar. Motorway speeds are not at all unpleasant ... I don't notice any drone.

Performance-wise, perhaps a placebo effect until the swept downpipe is fitted, but the spool-up is a lot quicker, so earlier. That's dramatic on an old(er) 900 with the Garrett turbo, as opposed to the quick spooling Mitubishi turbos on the later Classic 900s (post-1990?).
 

·
Registered
Joined
·
528 Posts
from a HP stand point the 2.5" is good up to 350HP. About 375-400HP a 3" system is needed.

Now as for how the turbo spools the 3" will let the turbo spool slightly faster, but if you remove the bottle neck at the turbo elbow the system is good for lot's of HP.

If you are looking for all out performance and you have moded everything else and you want the last bit of HP remaining hidden then the full 3" system will help.

A 3" system doesn't have to be any louder than a 2.5 you just need to find the right muffler to quite it down more.

The 3" system does space out the pulses more because the exhaust pulses are able to stay shorter vs being squeezed into a 2.5" pipe which makes the pulse longer especially if the turbo has a 3" flange instead of a 2-2.5

I ordered my new cat. 3" metalcat. should be here in November. Not sure what muffler yet. I like a quite car at idle but with a smooth tone at boost.

was looking at the new flowmaster 44super. think it's going to be to loud though.
 

·
Banned
Joined
·
5,841 Posts
Are the metalcat from Australia?

In the UK any car made before 1993 does not need a CAT by law, well so far:lol:

If you want a silent exhaust system then you will drop some power, its that simple.

You could have a noise cancellation exhaust but that would be very, very long and complex and still reduce power further.

I say enjoy the sound, the c900 has one of the nicest sounding 4 in line cylinder engines, that and the Sterling engines and boxer engines, I like the fullness of the sounds.

As for motor way or free way driving your brain will block the engine sound out after some time, its the lower sounds of the tires you brain can't block out as they travel into your body and make you feel sick.

Good quiet tires are your best friends on the motorway;)
 

·
Registered
Joined
·
528 Posts
yup, its from Aussie. Should be here 2 more weeks. The company keeps 2-2.5in stock but not the 3".

The company is very hard to get a hold of. the US distributor is also very hard to deal with.

Anyhow, the idea is the have a quite car at idle, so when you just ripped by the policeman and he pulls you over for a loud exhaust, you can say with a very dumb look on your face what loud exhaust the car is running and I can barely even hear it.

Right now the exhaust is just about falling off. The last really hard throttle push burst the pipe right in front of the muffler. Literally blew the pipe outwards all around. So, needless to say the pipe is very thin, and it's being held together with stove pipe and a constant pressure hose clamp. :nono;

On my wish list I have a 3" exhaust listed and limited slip. Both of which I have in my possession just not in the car yet. The work shop is full with a 900turbo head job. Once this is out the door I'll fit the exhaust and LSD.
 

·
Registered
Joined
·
491 Posts
the same happened to mine!!! but a spirited corner torqued it in half in the same place, the clamps were doing good until I went through a puddle and ripped the whole darned thing off including most of one of the muffle hangers. No one here (at least the 2 major shops) will make work on saabs exhaust...or brakes. I asked a guy if he could make one since a replacement cost 600!!! and he was like no. And I was like why not, its soooo simple and there's like one little bend over the axle, and he said that was the hard part, pipes can only bend so much. Well I figured they made them that way somehow! :roll:

So now it creaks, rattles, and scares me. any suggestions?
-Alex
 
1 - 13 of 13 Posts
Top