Are they all interchangeable? I need to find a replacement and want to know if I need to look for a specific model when looking for used? My son's car is a '02 Base with manual transmission. Thanks

According to realoem, it appears that they all used the same manifold.

I looked on RealOEM and was a little unclear with some of the numbers superseding others, etc.

I don't image there is a difference but I'm frequently wrong when I assume so I thought I'd look for some first hand experience. Thanks

Yup, exactly the same. Put my old R53 header on my R50 due to it rusting out, same specs.

I believe the answer is no, but is this also the case for the catback? I have an r53, 2004cooper s, and am looking to replace the rest of the exhaust (catback) from a salvage yard, but want to verify that I have to buy one from another S.

Thanks!

From past posts here, the manifold is the same for all the Gen1 cars. The big difference between the R52 and the R53 is that the R52 has a flat spot where the pipe crosses over the convertible under body x-brace.

Yes, you need the S catback. 'facelift' 05/06 works, but you have to move/adjust one or more of the hangers.

You said your son's car was an 02 R50 so you would need a cat-back muffler system from up to a 04 R50/Justa, I believe as the hangers changed with what we call the 05/06 "facelift" years.

From past postings, the manifold should be the same.