Frankly, I'm very interested to see what a mature system for the N55 looks like. IMO, that engine could provide phenomenal tuning value. Only need one DP, ICs can't be too different from what's on the market... I could see 400whp out of the N55 for $3,000 (IC, DP, Tune).
The N63 should be beastly
Edit: also, the new ZF 8 speed is fairly robust so.... one less bottleneck