I have two stainless steel Magnaflow mufflers for sale in the Dallas - Ft Worth area (i.e., Texas). I'd prefer to sell these locally or for the seller to come pick them up. Make a reasonable offer, and they're yours.
They came installed on my new-to-me E60 M5, so each muffler has the appropriate left/right hangers and pipe bends for an E60 M5. The mufflers are universal mufflers (i.e., not specifically made for E60 M5s). Thus, if you wanted to run them on something else, you could just have your shop re-work the pipes and hangers.
The mufflers also come with the installed tips. I believe they are E60 M5 tips. If not, they look very much like the E60 M5 tips.
On my car, with no center resonator and an X-pipe, the mufflers were noticably louder than stock and produce a good sounding, low rumble. At wide open throttle they sounded even better. There are a bunch of videos on YouTube that'll give you an idea how they sound.
I'm selling because my car has no center resonator and an X-pipe. The whole set-up, although quieter than the Ferraris and Lambos I see/hear around town, drew too much attention. I'm currently running stock mufflers, no center resonator, and an X-pipe, and the set-up is still just a little bit lound for my tastes.
Here is pic of the mufflers: