Full custom exhaust for Scirocco R

[majkilipa89]

Hi everybody,

I'm about to leave my car at the garage and order full custom exhaust ( including downpipe ). Have anyone done something like this yet? My question is about the cat issue- what about stock ECU? I want to delete cat and have straight pipes without any narrow spots.

Are there any tricks to solve it? Is a remap needed as well?

Thanks,
Michael.

[RoccoScientist]

You should get a remap if you go through with your plans. The stock ECU map will not be optimal for such a drastic change on the exhaust side and you might lose both torque and power compared to having the stock exhaust.

[Strat]

You should get a remap if you go through with your plans. The stock ECU map will not be optimal for such a drastic change on the exhaust side and you might lose both torque and power compared to having the stock exhaust.

That is incorrect.

I had the full APR system, downpipe + catback, and there was no issues with power/torque.

If anything it was slightly more aggresive accelerating than stock. The only thing is you will get the engine management light flash up, because the cat has been replaced with a sport cat and it doesnt know this. However, you can live quite happily with that on.

It is true to get the full effect and benefit of such as system you will want to get it remapped, it will however not be bad for the car to not do so.

[RoccoScientist]

The actual effects of having a stock ECU map and a custom exhaust of course depend on how much the back pressure is lowered. However, especially if you decat the car there's really no reason to expect the stock map to be up to the task anymore. It might of course be able to adjust the f/a ratio correctly even without the cat, but I wouldn't bet my money on it - it all depends on what parameters the ECU is relying on. In any case, the effects may not be drastic and may only be noticeable on a dyno (a difference of 10 PS is very difficult to notice in a car with 200+ PS) and while it's true it might not be bad for the car per se, I believe there's a reason why exhaust manufacturers like Milltek say that fitting a turboback exhaust requires an ECU remap:

"The cat-back system can be fitted to a car in standard tune (without an ECU remap) but if you fit the full turbo-back system you will require an ECU remap to ensure a smooth and trouble-free integration with the engine management system."

Edit: And if personal experiences account for something, one Audi A4 1.8 TSI (160 PS) owner reported on another site that he lost some low-rpm torque when he changed to a turboback system. In the end, he decided to change back to the stock exhaust. It would've been interesting to see if the dyno agreed with him or not.

[majkilipa89]

Thanks guys for such a interesting replies. I will make a remap as soon as the new exhaust system is on.

My question is- what is the solution for avoiding the appearance of "check engine" light when the cat is removed?

Strat, did you have sport cat in your ride? Do you know any solution for removing the cat completely?

[scottyroc]

Basically you would need someone to map out the O2 sensors.

[johnjm]

My 2.0 TSI has full exhaust system, no CATs at all. Stock ECU and not engine lights.

[scottyroc]

My 2.0 TSI has full exhaust system, no CATs at all. Stock ECU and not engine lights.

Must admit my old Tsi never suffered either