I have a 1999 M3 with a Brembo GT 355mm; I am having some issues with the front brakes. Vibration that gets worse with heat. I think my best bet is going to be to replace the rotors with a slotted vs. the current cross-drilled rotors (this is primarily a street car). Who do you guys like in NA that can get me 355mm slotted rotors and hardware? Can I replace the rotors myself or are special tools required to the get the bolts all on at the right torque?

Try here: http://www.racingbrake.com/Brembo_Stoptech_s/4400.htm

Prices are very good on the slotted replacement rings.

It's easy to do it yourself. You need a big hex head socket to get the calipers off, and a smallish one to remove the rotor rings. Sorry I don't remember the sizes. You need some red loctite for the new hardware, and a in/lb torque wrench to set the new bolts.