Soon, I'm going to measure this. I'll first make several passes with the stock cat, then go to the pits, swap it out for a test pipe, and immediately making several more passes.

Anyone care to guess what this is worth? I'm guessing 1-1.5 mph on average.

 

Off course everyone cares about the gains. Thanks for taking your time to do that.
your trap speed target seems very feasible in my opinion.

Carlos

 

i would like to know, since im about to put a testpipe on to replace a high flow cat, then hit up the track again.

 

awesome test... let us know the results.

 

Yes, it's 10-15whp, which would be 1-1.5mph.

 

It would depend on your mods. While my car was stock with a dynoflash I gained .2 and 2.5 mph.

 

When I removed the cat I had to turn down the boost because it was 1-2 psi more. Heck yes more power - but you may loose most of it when you turn the boost back where it was

 

I hope that's not the case. That suggests that a test pipe offers little or no whp gain over the factory cat, when the boost levels are the same.

 

That's not the case. The stock cat is very restrictive - a test pipe does not get its power from increased boost.

 

I am all about this test but the test is somewhat flawed. It would be much easier to test on an automatic car, but unless you are a great driver (and you probably are, but for arguments sake) shift points and launching can be a big factor. Sorry, just like to be devil's advocate. Good luck!

 

That's very true for ET consistency. But from my expereince, MPH is a lot more forgiving. For example, suppose you get a 1.7s 60ft time in one pass, then screw up on the next pass with a 2.0s 60 ft. Most likely, you'll be about 0.4s slower on the 2nd pass (a big difference). However, the mph will probably be very similar.

When I do this test, I'll put more weight on the MPH than the ET gain. Now if I can only get those damn rear bolts loosened, I'd be ready to do this.

 

So are you running an aftermarked cat back? The gains won't be as great running through the stock muffler.

 

Stock cat-back. Because I already have one loud car, I have no intention of getting a full TBE on the Evo. But I may eventually get an e-cutout on the downpipe for the drag strip (where I don't mind being loud).