I see advertisements of 2.25" collectors here and there and wonder if they've just measured the outside diameter. I truly need a header with a true 2.25" inside diameter collector. I have a Skunk2 2.25" test pipe, and want to mate a header to it, obviously a 2.5" header would be too big.

Has anybody actually seen a header with a real 2.25" collector?

 

yeah they make them all kinds of sizers. you have a test pipe now and what kind of headers? or the stock exhaust manifold?

 

This is on a JDM B16A. I have a 2.25" Skunk2 Test Pipe, and that's the inside diameter, I measured it. I have the stock B16 manifold right now.

 

as long as the testpipe will fit over the header you will be fine. the header has a o ring or "donut" gasket to center and seal the connection.

 

Right, see I really want a 2.5" header, but I don't want to have to buy another test pipe. I bought the 2.25" test pipe because I used to have a Mugen B16A header (50mm collector) and plus I can run my stock manifold with it. I wonder if a 2.5" header would seal with the 2.25" test pipe. I would eventually get a 2.5" test pipe for better flow though, but I can't buy them both at the same time....because then I would have to save longer lol.

 

I bought a 2.5" header. The End.