DoctorT, I called Krown and my quote was $119.99 + HST (around $135). I think going with Krown which has a good reputation with the higher end cars and who can provide a no-drill option (I was told by someone he went to Rust Check, told them not to drill and they still did it anyway) is worth the extra cost.
As an aside, I'm thinking of going with the BMW Performance air intake in addition to the Dinan exhaust system. After researching a lot with the HPFP and of the times I've had HPFP problems (long drives in hot weather), it seems to be overheating turbos. The BMW turbos run insanely hot and I think cooling it down will definitely help.