A bit of forum digging for ya.... there should be a BMW part number legible on the flat section of the flanges
- Euro M3s before 03/2005 use Catless Headers.
- Euro M3s after 03/2005 use CSL headers.
- Euro Z4Ms always used CSL headers.
My garage floor showing USA headers (old) and Z4M CSL headers (newish) prior to installation - note the aforementioned flat spot. Any euro header will really wake up the car and butt dyno!
