I notice aftermarket companies make vtec and non-vtec versions of exhaust systems for the 4th gen. What are the main differences of the two versions? Is the length or mounting points different? Perhaps different flange on the cat? I recently did a h22a swap and still using the original Si exhaust. Just curious if either version would work.

 

From what Ive gathered searching this topic ...the only difference is the rear flange on the cat , which most people say that you can do minimal modifications to make either one fit.

 

Either one works fine, had both on my car, at first I thought there was a difference, but its at most maybe 1/2 inch in length, or a tiny bit larger holes for the bolts on the rear of the cat.

 

Doesn't it make a difference? Like the H23A1 engine is the non-vtec engine and the H22A1 engine is the VTEC engine. I know that for the intake manifolds, the flanges don't line up... isn't it the same for the exhaust manifold? Or are you guys talking about cat-backs and not the header...?

 

I don't think cat-backs should make a difference. Headers are def not interchangeable

 

Sorry for not being clear. I was referring to the catback exhaust and not the header. I used the JDM exhaust manifold and the short a-pipe during the swap and made a custom cat to bolt up correctly to the existing oem catback exhaust. Had I known the difference in the rear cat flange, I could have made the rear flange more universal to fit the different versions of catbacks.