Would stock piping, performance cat, and a twin-loop muffler on a 2000 civic si be adequate for proper exhaust flow? Also, Is it true that you can use a CTR intake cam, and replace your stock exhaust cam with the OEM intake cam?

 

Stock exhausts are usually very retrictive. You might want to get a new cat and some bigger piping done to go with that muffler.

Intake and exhaust cams are different I would think.

 

Get a 2.25 piping.
If your gonna get the CTR intake cam might as well get the exhaust cam as well.

 

betweeen 2-1/4" or 2-1/2" piping is good for NA & 3" for turbo.
as far cams for a NA, CTR and ITR combo work good.

 

I'd get piping as well, isn't gonna' run you too much more than what you are spending already. Also, I don't think that you can use an intake cam for an intake cam.....they are different, no :eh:?

 

If you want good flow, then get better piping than stock. A good header like a JDM 4-1 or DC jdm 4-1 will be nice, too.

As for the cam question, you can replace just the intake cam and leave the exhaust one. Do not use the intake cam on the exhaust side. It doesn't work like that. But since you have to do quite a bit of work to install the CTR intake cam, might as well install the exhaust cam, too.