Welcome to the site. There are a few choices for an exhaust. Do a search and you'll turn up lots of info. More than I could cover here. BTW, I have a custom exhaust which you'll also find by using the search function. Again, welcome and congratulations on acquiring a great automobile.
Hey- the F is hard to compare. I had the e90 M3 manual and the e60 M5 manual as well. It feels significantly more torquey than the M3. It is more of a "muscle car" than an all out athlete like the M3. The ride is considerably smoother than the M3 in my experience. I find it more enjoyable in daily driving situations then the M3. The M5 is too hard to compare as it's bigger and has a V-10 so not really in same class. Only thing I miss really is a true manual transmission. That being said, the 8-speed paddle shift is fantastic under full throttle! And, oohhh that engine sound when the second air intake opens up!!! Glorious!Martinisf welcome! I am an AMG guy originally... How does the F compare with your M? Which Ms have you owned? Sorry I dont have any info re exhaust, but others will or sure.