67mm (2.5inch) inlet size works for the MPE.
I got fake Akrapovic tips. Happy with the quality given the price. They are a touch larger than I would like at 101mm on the outlet side
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
They look like this on my car (with M diffuser).
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[FONT="Arial"] M235i 6 speed, MGM. Wavetrac LSD with altered final drive ratio, MPE, MPK Airbox, side skirts, diffuser, Dinan springs, LCAs.