[Cavpilot2k]

The key is to find a mod-friendly dealer.
For instance, my dealer is still a Dinan dealer too. They have never balked at any warranty repair and I've had a Dinan Stage 2 tune (that they installed) for years.
They actually had to replace my manual transmission (done under warranty). If they wanted to be dicks, they could have said that the additional stresses caused by the tune were at fault and refuse to warranty it, but they never blinked an eye, and neither did BMWNA.

Now I can't say that would be the same if I had a self-installed JB4 on it at the time, but I think this dealership is generally mod friendly, so I go to them with confidence. When I get an M2 eventually, I have already spoken to them about a Fabspeed DP, and there was no "you're gonna shoot your eye out with that thing!" My SA just said he doesn't recommend it because it can be a pain to pass emissions sometimes, but nothing about affecting warranty.

Bottom line: it's all about the dealership you choose to use.