I was looking at rear bumpers and was woundering if a (05) rear coupe diffuser fits on a (05) Rear sedan bumper

I'm thinkink about getting split exhaust system instead of the regular sedan type

 

It would not be a direct fit, you'd need to modify it quite a bit to fit. You would be better off getting an 03-04 bumper (and mudguards) and putting an Ionic Nismo replica rear on it and cutting out an opening on the passenger side for the exhaust opening. Would look similar to this:

 

i was hoping to use the stock bumper but thanks ill probably do that when the time comes.

 

Strafe is working on a Nismo rear lip that will fit the 05-06 bumper but it may not look the same as an 03-04 bumper with the Nismo lip because the 05-06 bumper has a lip built into it whereas the 03-04 does not.

 

And that'll be ready sometime in 2015?