Irishace, I think you are right to run the car stock for a while before you crank up the power. A stock E46 M3 is pretty damn fast. I don't know how much track time you've had, but the first times I took my car to the track I found the throttle to be somewhat of an enemy. The very first thing you should upgrade, IMO, before the suspension, is the brakes. My first track day with my car was at VIR with the car stock. I boiled my brake fluid and had a change-your-underwear sort of moment when the brakes faded at 135mph. The E46 is not light, and the stock brakes will not hold up if you drive it hard on a brake-intense track. I've had no worries with my BBK, but SS lines, pads, etc might be fine, especially if you stripped some weight out of the car.
I went SC at a time when turbos really weren't out there for this car. I've got about 110K miles on this motor (60K miles and a bunch of track days since putting on the blower) and it has held up well. I have had some heat issues on a couple of very hot days down here; that might not be such a problem for you up there, but agree w the others that the biggest issue with any F/I on the track will be cooling it. I will also say that now that I'm used to 462hp, it is an utter blast on the track. I really can't imagine what I'd do with more, but if this motor ever blows up I'll probably have HPF rebuild it and turbo it, so maybe I'll get to find out.
2003 LSB M3, SMG, Dinan S3-R conversion, incl. 3.91 differential
Brembo BBK w. custom-painted LSB calipers
Dinan-JRZ's, Turner adjustable camber plates, Dinan wheels for street, D-force LTW's for track
JL Audio ZR-650 CSi's, JL Audio 300/2 in front
JLAudio Stealthboxes, JL Audio 250/1 in back
Audiocontrol 3XS crossover, Audiocontrol EQS
My other car is a Fisker Karma