Been searching all the forums but can't find the answer.

I have an 2007 550i and want to know if a 2006 stock M5 exhaust would fit?

 

Nope

 

a good shop can cut and weld pieces to MAKE it fit if you REALLY want to or already HAVE the exhaust but I wouldn't bother buying the actual M5 exhaust. (unless u got it super cheap) Weather its the look, or sound, or reduction of back pressure you're going for, a muffler shop can pretty much fab up what you want....just make sure they use MANDREL bends and not crush bends.

 

Take a look at the Dinan.

 

what gains will you get from adding the stock M5 exhaust to your 550? might not be worth the time and money spent, just to say you have an exhaust from an M5