Dinan is a tuner in the US. They are somewhat similar to Schnitzer or Alpina. They make excellent quality products and specialize in high performance upgrades that not only make the car faster, but most of the time, make the car even more drivable for daily situations as well. Jim Comforti and Autothority are other US tuners that may have plans for the MINI as well.
I spoke with a Dinan rep last month, and they were preparing to sign a deal with John Cooper Garages to import and co-develop products. I have not heard any definite details yet. Mini mania has developed a turbo for the cooper, and are planning an SMG tranny for the S. When I get more details on warranty and products from Dinan, I'll try and let you know.
I see you're in Baltimore so you aren't that far from Philly. Helix Motorsport will be making some aftermarket goodies for the MINI too. Most noteworthy is they are developing a chip from GAIC. GAIC makes some of the best chips out there.