Here is my 228i with the M235i MPE!
Sounds no different from the 328i MPE from what I can tell on Youtube, but I prefer the dual exhaust look.
You'll need the M235i rear bumper insert ($100 shipped from SunAuto), extend the two hangers on the muffler (it lines up, but you'll need to extend them so there is no tension), and an exhaust fabricator to weld and connect the muffler to the piping since it does not line up perfectly.
Took about 90 minutes to install, just find a shop that fabricates exhausts.