[Joe240]

The downpipe is the same for the A90 Supra (actually this downpipe wasn't listed as for the Z4 when I originally purchased it, it was listed as compatible with the A90). I can't vouch for the m340i downpipe as I haven't seen it. The reason it works with the A90 is because they share a chassis. According to realoem.com though, the m340i (starting March 2019 build date) shares the same part number for the downpipe with the g29 z4 so should be safe to assume they are interchangeable.