[BKK 5]

I've seen multiple M5 rear diffusors running on non-M5's and think they look great. I'm looking to add this to my m-sport bumper, but the local car shop has stated that the M5 rear diffusor is "shorter" and not a direct fit.

Is this true? If so, what needs to modified to make this happen? I already know the exhaust needs to be modified to fit the more narrow cut-outs, but I didn't know the actual diffusor had fitment issues.

Thanks for your help!