[UZD4SX]

hi everyone,i m new to this site.
its a great site, covered pretty much things about k20a,i love it.
currently im planning to put a k20a into my ek.
just wondering whats the best exhaust size going with?3inch or 2.5inch?
any help with be appreciated.
what brand you guys are running?give some ideas,thanks.

 

[TeamPacman]

2.5 inch on a ES muffler

 

[drhonda]

I'll be running 2.5" with comptech muffler.

 

[V8KO]

2.5 inch on a ES muffler

Any particular reason why? Whats your opinion on test pipe versus high flow cat here?

Thanks.

 

[K2e2vin]

high flow cat is still restrictive, its flow is not as high as a testpipe. ive got a 2.5" exhaust on a magnaflow style muffler, sounds nice but too loud. if you want it quieter then get the high flow cat.

 

[Dark2k1]

Ok about me...

I have the 4-2-1 DC header without cat..

I gonna remake my exhaust line with 2.5 mandrel tubing..

But... if I want to have a quiet sound at low RPM.... can I have a solution without considering a cat..

I think to put 2 high flow resonator



So i thought also about put a 3 inch high flow cat, and go with 2,5 inch after the cat... how many whp you think I could loose ??

 

[DamonRSX]

So i thought also about put a 3 inch high flow cat, and go with 2,5 inch after the cat... how many whp you think I could loose ??

I did exactly that, with 2.5 mandrel, 18" resonator and ES tuning muffler. I don't think it matters much, but after I had it, I found out that the flow on the 2.5 and 3" high flow cats are the same, and that the change in diameter causes turbulence that might not be good. It is loud, but not too loud, it sounds really good to me, and I only liked a few after market exhausts I've heard. It gurgles a little when getting off the gas, which I expected, and it's a little raspy, which I also expected, but at lower RPMs (<4000), it's very deep and smooth as butter. At 4000 RPM in particular, I get a cabin drone, which I guess is resonance from vibrations due to the mounts, but someone did tell me that a flex pipe would help, I have all welded hard pipe with a hasport header. Overall, I think I spent too much time worrying about what to do for exhaust, it will be loud no matter what you do.