Bill,
I'm pretty sure the base model and the sport touring is a bit different. I know the sport touring has the bigger brakes and it also has the VDC option. As far as I'm concerned the suspension, brakes and springs are excellent and not worthy of changing. As far as horse power. The CAI, Exhaust, HFC and Headers will give the car an extra 60 horse. Now the question is, where is that power distrubuted? The 370 Z in my opinion is the ultimate package for the buck. I freakin love my 370. Working on getting the upgrades done and when I do I will update you with the pre and post Dyno. Steve