Hoe different are they can u modify a 5th gen header to fit a fourth gen? And vice versa? PS anyone wanna sell me a greddy header for a fourth gen?

 

A H22A1 header is interchangeable with a H22A4. Don't quote me on this but I'm pretty sure.

 

The difference would be on the lower section of the header. The head flange is the exact same but it's just the lower section that will be different. The same is even on the SE and SH on 5th gens. The SH is longer on the downpipe section, I put an SH dc header on a 5th gen and had to cut it and shorten it in order to fit the SE. So to answer your question, yes, it will bolt up but you will have to either cut it or lengthen it which is not hard at all.

 

you really shouldnt respond when you dont know the answer.

they are not interchangable.. bolt on wise.