Elberoth

I'm gonna do the custom exhaust on my car soon.

I heard somewhere that the way the OE cat is mounted on 1.8T engines is worst imaginable - straight to the turbo.

Do you thing that moving the cat 1m down the pipe would be beneficial ? I could replace the OE cat with random-tech high flow 2,5" cat for example. I can even do a 3" downpipe between the turbo and the cat.

Any ideas ?

SameerP

what you could do is have a ceramic 3" in/out Catco cat put somewhere downstream, like replacing the resonator, or welded into a mid-pipe. Id just leave the O2's in the test pipe and use an emulator to eliminate the CEL.

That is what i plan to do in the near future. Since the temps are lower, a $200 catco is all you need. Look at what the GTI folks are doing.

Cheers,
Sameer

Elberoth

Will I gain anything just by moving the stock one ?

Audi2ptzero

But you will still have the same back pressure.

Elberoth

I thought that maybe putting a 3" downpipe before the cat would help somehow

SameerP

its curved significantly on the outlet side. So to use it, id assume you cannot just weld it into a mid-pipe. A 3" in/out catco is just straight in and straight out.

Besides, you do not want the narrow restrictions if you are going for power. To have a 3" DP is great, but then why have a 2" inlet, 2.25" outlet OEM cat as a bottleneck in the middle of your system?

Cheers,
Sameer

Elberoth

You're right. 2,5" Hi-Flow cat will set me back 200$ - is it a cost efective upgrade ?

AXE

The turbo spools noticeabley quicker.

I think it's definately worth it.

Elberoth

Does it tapper to 2,5" after the cat ?

AXE

No .. 3" all the way through