Like the title says. I want to compare it to my B16A exhaust manifold collector. I know they're both 2" OD, it's the ID that I'm curious about. The ID of the B16A manifold is 1.5", which is tiny of course. If the ITR is the same, that's pretty impressive they got 195hp using that manifold. But if it's bigger, I want to get my hands on one.

Another thing: is the USDM '00-01 exhaust manifold collector the same size as the '97-99? I know they changed the cams, so just wondering.

 

Same size between the years.

 

stock 00 USDM ITR header

 

THANK YOU, Relic1!!!

That's exactly what I needed to see. The ID of the USDM ITR collector is 1.5" just like the B16A. I know the A-pipe on the exhaust manifold flows better, but the difference would be negligible if used on a B16A (I'm guessing so).

*When I say 1.5", it's really 40mm, which is 1.57", and when I say 2", it's really 50mm, which is 1.97".