I have some info...
Houston has some decent shops. Personally I haven't had luck with M Power Performance and would never recommend them to anyone.
However, I like Clown Shoe Motorsports in Dallas, contact them for your coilovers and proper installation with corner balancing.
There is a new company out that has had some stunning reviews, JailBreak Tuning, google them. They send you a cable and you download your tune yourself, after payment of course.
There was an exhaust on Craigslist for your car, no affiliation, but it might be a spot to check.
Welcome to Houston, check out the M Club of Houston...check out the local BMW CCA chapter site...enjoy!