So i recently went from a 60mm exhaust to a 70mm exhaust on my N/A setup. Before, i also had a 60mm test pipe as well (63.5mm to be exact) Now the same test pipe is on this 70mm exhaust.

Now i know the whole, i need to match up 70 with 70 etc. but will upgrading from 63.5 to 70mm really make much/any difference?

One guy (has a GTO) explained it to me that, no matter how big my exhaust is, my exhaust restriction is 63.5mm because of the test pipe, so it doesnt matter how big my exhaust is after it, you can only fit so much air through that test pipe, therefore, if i want my exhaust to make any power, i need to upgrade the test pipe. But wouldnt that be like saying the collector on my comptech header is 63mm so having a larger than 63mm exhaust be no help, since i can only fit so much air through the 63mm header collector

I just want to know if I would be benefitting my flow substantially (as far as s2k exhausts go) by upping to a 70mm tp

I searched around, but just found people saying, yes 70mm is better, and dont go 70 > 60 due to bottlenecking but thats about it. I dont know if its worth it to sell my 63mm tp and pop a 70 on

 

Technically you would get more top end power with a 70, but i doubt it'd be really noticeable..? someone with more knowledge can chime in, but if your header stays a 63, its really only two feet more of pipe..?

 

If you have a 63mm header don't bother with changing your test pipe. The system is limited by the header.

 

i believe someone dyno'd their s with cai and exhaust with cat and the same car same day with the high flow berk and there was a 5 hp gain.

 

^^ oh ya no doubt that a HFC/TP will make a good amount of power over the stock cat, i just want to know if it'd be worth it to upgrade to 70TP with my 70exhaust and 63header. Im thinking the same as Splatter85, theres no reason to upgrade the TP since its already limited by the header

 

i went from a 63 to a 70 BECAUSE my header outlet was 65 and my exhaust is 70. so having a 63 mm tp i thought that was bad. so i got a 70 mm. so now it is 65>70>70, before that it was 65>63>70. guess what. It feels the same!!!! sure i probably gained 2whp but that is within dyno error. if going from a stock cat to a tp will only give about 5whp, going to a larger size didnt matter that much. but if you are one of those anal guys, who needs every last bit of power with bolt-ons then by all means, go ahead. but to me, there was not very much benefit for going to a larger size. it's your car and your money, and this is my experience and opinion.

 

I would go to a 70mm TP but I doubt the diference would be noticable,

 

how about you sell me your 63mm and buy a 70 haha few people have flaked out on me and the only offer I have on the table is for a Berks - which isnt a bad deal, but 100 bucks for a pipe does make me sort of sad..

 

pretty much sums it up..but its ultimately up to you...as ans2k said also, there was barely any difference in feel..save that money and put it somewhere else in that case

 

thanks for the replies guys, Ill just say eff it, and use that money elsewhere. I dont want to go through all that trouble for MAYBE a hp or 2 more