Have you double checked spark plugs? How old and which are they?
Honestly now that you mention this and thinking about how the car feels you might be right, it does feel like two dry surfaces spinning and losing grip.It could also be the clutch starting to slip. 6th gear pulls are hard on the drivetrain.
It's likely that the clutch was getting worn, and when you replaced the plugs, the extra power finally overwhelmed the clutch.Honestly now that you mention this and thinking about how the car feels you might be right, it does feel like two dry surfaces spinning and losing grip.
Yes, it sounds like the clutch/flywheel can't take the additional power. You will need to upgrade the clutch to accommodate the additional power. I'm not sure how much power the stock clutch can take before it starts slipping.I went to the garage again today, took the car out for a drive and we've come to the conclusion that the issue is definetly something mechanical (probably because of the increase in torque?).
We reverted the stage 1 remap and now the car is stock again and no more issues. Also I noticed that the slight vibrations I was feeling in the clutch pedal and gear shifter at certain RPMs is gone now.
So I guess it's either a bad remap or the clutch/flywheel can't handle torque increase?
That could definitely be a factor. In reality though, I haven't been able to find reliable information on how much power the stock clutch can take in either the 2.0 or 2.8 cars.It's not the stock clutch and flywheel, from what service history I have from the previous owner he replaced them about 25k miles ago. I don't with what brand but I suspect he got the cheapest he could find.