I just installed a downpipe and a testpipe on a friends car. They are both 3" and connected to the stock cat back for now. For those of you who have done this, what performance related differences did you notice initially? For now, I have noticed the turbo seems just a touch louder, the drone of the exhaust still sounds stock. Also, when we took his car for a test drive, the turbo seemed to spool a little quicker. We aren't really certain if it pulls harder. So far we only tried a few 2nd and 3rd gear pulls for comparison. I just want to see if what we are noticing is similar to what you guys have noticed.

 

i installed the ams downpipe and hf cat and i noticed a big difference in top end power.

 

Catback and testpipe made a noticable difference the downpipe didn't do didly.....

 

well you still have a huge restriction with the stock exhaust..so you wont see a big diffrence...the purpose of doing the exhaust portion is to reduce back pressure.....you still have the stock exhaust which has all kinds of crazy bends/taper downs

 

Getting rid of the cat had to release some restriction. I guess we will know for sure when he hits the track this weekend. One thing is certain, with the cat gone there has to be some better flow. We will tune it as is and see what the gains are. I think with stock he trapped 98mph, with tune and MBC he trapped 105. Hopefully he sees 108 - 110 now. Next step will be the cat back exhaust. Hopefully this will be good experience for those thinking about upgrading.

 

noticed a big diff with test pipe + DP

 

^ same.

 

wasnt here a guy a few months back running around 400 whp with stock cat??
people say our cat flows pretty damn well for a stock cat.