Exhaust Size Dilemma.
 

I hope you guys can help me out here cuz i don't know what to do. This is going to be my first turbo setup so i cant rely on experience.
First off, I will be putting an IHI RHB5, boosted at 8psi, on a stock d16y8. Now, i was planning to go with a 2.5" exhaust, however a friend from a different club is selling his exhaust. It is a full exhaust from the headers back, full maganaflow stainless steel, high flow cat, resonator and muffler. Only catch is it is 2.25".
Will this be too small for my setup? I know for the turbo the bigger the better, but its not THAT big of a difference from 2.5" is it? However i never had turbo before so i don't know.
Thanks for any help.

Re: Exhaust Size Dilemma.
 

I wanted to go with 2.5... but same thing happened to me. I just went with 2.25. I have nothing to compare it to, but it works fairly nicely. It's a small enough turbo where I don't really think it'll matter all too much.

My buddy had a 3'' exhaust on his probe (rhb5 too), kept spiking once we put that on to about 10 psi, and this was w/o a boost controller.

Korkey Bell seems to think that 2.25 should be good for your power level, so I would say you're fine ;)

Re: Exhaust Size Dilemma.
 

Anything is better than stock, 2.25 will be fine for the ihi.

Re: Exhaust Size Dilemma.
 

im going to be running 2 inch exaust all the way back with a fart can at the end

Re: Exhaust Size Dilemma.
 

i wouldnt run anything smaller than 2.5 but thats me....i also usually dont run any exhaust lol

Re: Exhaust Size Dilemma.
 

I had 2.25 on my civic, and when I upgraded to 2.5 it was alot different. I had more power than I did with 2.25" exhaust.

Re: Exhaust Size Dilemma.
 

I had 2.25" on my 14b setup. Went to Homemade bent(slash cuts) 3" with a 2.5" muffler and noticed AWORLD of difference. I datalogged bosst 3-400 rpm earlier. DEFINITLY would never go under 2.5. Save you money or make it yourself. You may say I'm only getting an IHI, but in the future you WILL want to upgrade. Do it right the first time!!!

Re: Exhaust Size Dilemma.
 

Getting mixed opinions everywhere. Well the guy wants to wait a while before he sells, so i still have some time to decide, and or, find a better deal. If i can find a 2.5" for around the same price, ill get it, if not i think i just might get 2.25". I guess i could always resell it.

Re: Exhaust Size Dilemma.
 

werd 3" exhaust ownz you.

I pretty much ---- my pants from the difference it made over my 2.25". Much quicker spool

Re: Exhaust Size Dilemma.
 

I wouldnt do anything under 2.5in, especially the downpipe. It may not make a huge difference in the world on a RHb5, but later on when you plan on upgrading the turbo (which you will because rhb5's suck) you will already be set.

I'm a firm beleiver in open downpipe myself :)