I heard that 2.5" piping is the best overall but i dont want it too loud so i got 2 1/4" straight piping from manifold back. i'm planning to get a muffler with it too. hopefully the noise will be SCCA legal.

itll depend on your muffler setup. If your just using 1 muffler it will probably be pretty loud.

There's a lot of exhaust options to get a good noise/power/weight ratio. If you haven't bought the exhaust yet, let us know what you're trying to get from it and where you'll be racing it. That will make recommendations a lot easier.



I'm running a dual outlet header to dual presilencers into a straight through muffler. It's actually ridiculously quiet but makes a strong power band through all rpms (less high end than with a full dual or single). Just as an example.

It's a single setup exhaust. im getting a muffler soon.

I've got rb header->rb presilencer->2.5" single pipe->single 2.5" (7" canister) magnaflow straight-through muffler



I say it's bearable, I can hold a conversation with my passenger. It's no louder than many v8 and honda ricers with aftermarket exhausts that I see plenty of.

well as i said im gonna be running this single straight pipie satup on SCCA race days. the thing is i dont think it will be that loud b/c its ony 2.25" but should i get a resonator put on before the muffler?

i would, because you are working on a straight pipe it will be much louder, cutting back on the noise can only make things better. Anyways, its better to be a sleeper than a loud fart reving civic. but thats just me

What is an SCCA race day? Are you talking autocross or club racing or drift events or what? What is the max dB allowed in the kind of racing you plan to do? Most have VERY leniant restrictions and, unless you're running open headers, you will easily be under any requirement.



If you're running the stock manifold still, I wouldn't worry about it either way. That is the most restrictive piece in the stock system and I'd be surprised if anyone complains at any event.

SCCA race day is for auto X it's july for me, I'm thinking if it isn't too loud i'll keep it on, my mufflers already have 5 holes each...lol



yeah i'm running a stock manifold, a lil port match im probably going to put a resonator definately.



got my muffler today:

https://www.wanganmidnight.com/forum...9929_thumb.jpg

3.5 is hella loud https://www.nopistons.com/forums/pub...#>/biggrin.png , but its great. It rattles peoples cars when I am next to them.