3 inch exhaust on my build?


*JDM Approved*
For those that have been following my build-up with all it's breaks, slips, faults, fuck-ups and all.
It's time for another question, lol.

I have had a few people tell me that I'll need a 3in exhaust now for the exhaust flow.
I have 2.5in now or atleast close to that. Greddy SP2 for 4dr GSR for those that don't know

What do you guys think?

For those that haven't followed up with my build but are good in this region or would like to help, check @ my build up thread to catch up.

3" would be too big; especially for a NA gsr. even with your mods, 2.5" will be fine. if you want to get bigger exhaust than that, get 70mm(2.75). 3" is just too much for a NA car. i believe there is an article on team integra that has a formula to figure out what size will be best for your setup


Super Duper Moderator
You don't want a 3 inch exhaust, those are for Tegs with superchargers or turbo's.
2.5 inch exhausts are for Tegs making 190whp or more all motor. You should get a 2.5 inch system, because your DC race header already has a 2.5 inch collector, and you don't want diameters to get smaller from the header, to the cat, to the exhaust. You want them to remain the same or get bigger, never smaller at any point. In your case, make it 2.5 all the way through, you'll be making the power to justify it.
That little bit of diameter does have an effect on the ability to extract exhaust gases from the head. Exhaust diameter has an affect on where you peak HP and TQ will be along the rpm range, and what it will be.
The Greddy SP2 isn't a full 2.5 inches, exhaust diameter is measured by the outside diameter of the piping. It's either a 2.36 or a 2.38 inch.

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*JDM Approved*
Ok phew.


*JDM Approved*
ok, I thought I was going crazy in my mind with about 5ppl sayin I needed 3inch exhaust

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