Effecting Performance ?
 

ok heres the deal, T25 turbo on a6, well i was running my str8 downpipe for a while and it ran hella smoother it seems before i got it connected to my 2 1/4" exhaust, it has a cat on there and muffler

my question is, how much power am i losing ? i noticed for the first couple days the undercar would smoke when im stopped, was this the underlining burning or was that the cat torching itself into the ground? heh ???

any help would be great, im about to install a 3" cutout right before the cat, if the cat affects it too much i will just get a full 3" exhaust with no cat. im trying to save money so please only tell me if you really know :P :-*

Re:Effecting Performance ?
 

cut out the cat and weld in a straight pipe.

Re:Effecting Performance ?
 

Every cat wins the restrictor2004 award (exepct the full flow racing cats).. Gut / dump the bitch :)

Re:Effecting Performance ?
 

You are losing a few HP. How much, all depends, if youre in the 1000hp range(theoretically speaking) cut that in half(with a stock exhaust and cat). The loss of HP goes up as the power goes up. That also has many variables, 1 inch exhaust? 4 inch? stock cat? mandrel bent? flange bottlenecks? etc.,etc.,etc.,

The underlining would burn if the exhaust was pointing straight at it, but at idle...seems kinda odd, maybe your running rich at idle?

The best exhaust on a forced induction vehicle, is of course NO exhaust, If I could run with just the O2 housing straight on my car, I would. Gas milage would suck due to the O2 sensor never getting an accurate reading, but hey, if you wanna play you gotta pay right?

Be carefull with those cutouts. Are you running an external or internal wastegate? If your running internal, the odds of you getting boost creep are greater. Also depends on what your displacement is. On 2.0L dsms we get boost creep on running a bigger downpipe, disconnected from the cat. Basically open exhaust. Creep aint pretty.

If youre installing a 3inch exhaust, why go with the cutout? I would just use the 3 inch cutout, and keep the stock exhaust and cat in place. Id also get an electrical cutout for those occasional races.

Good luck

Re:Effecting Performance ?
 

Man, I have some competition all of a sudden. It's okay, I plan on getting some things done tonight, expect some long posts from me.

A nice 2.5 inch exhaust with no crush bends will flow all you needs for that d16. Gut that cat, weld a pipe in it's place, having an open chamber cat will only create back pressure. The best upgrade on any turbo car is the "test pipe" one. No OBD2 on your ride so you're all good.

Keep us posted.

-ryan

Re:Effecting Performance ?
 

damn q, i never seen anyone post longer than you :)

thanks for the advice guys :)

Re:Effecting Performance ?
 

It can make a big difference. I had stock dx exhaust off an lsvtec...it was garbage, felt like a sohc completely offset vtec.
switched that up and it felt like a whole diff motor.
Quandie's advice is on imo. no cutouts no cat/hi flo cat and 2.5