For anyone looking for a great deal on a delete in the San Francisco bay area, I highly recommend "Exhaust Specialist" in Burlingame. The guy that does the work there, Louie, is fantastic to work with and has decades of experience. You can pull your car right onto the lift yourself, he never even sat in my car during the entire process. I wouldn't have had a problem if he did, but I'm sure many of you prefer to never hand over your keys.
Total process took just under 2 hours and he did it all for only $180, including the cost of the tips. YMMV on the price though of course. I'm not sure what brand of tips he got but they look to be pretty high quality. As for the sound? I can't believe I waited a month since purchase to get this done! I'll just echo the bulk of responses already in this thread, it sounds great, no drone and could be the best low-cost mod for your m5.
Here are the tips he used:
The before and after:
Old mixed with the new:
Close up view of the mounting method:
Final product: