[TSM330i]

All: I agree completely with a lower performance car. Daily I drive a 2000 Golf GL (yes, a 2.0 liter with a manual and 167K on it). I can throw that car around quite well at this point. I always say it's better to drive an under performing car at the limit rather than under driving a high performance car to really learn what you're doing. I also came from a 2006 Z06. I was really getting the hang of that car before the family expansion forced me to move to a 4-door car. Dynoed 443 rwhp and a little over 3100lbs. made the transition to my 330i very easy (I was a bit bored with it in stock form to be quite honest).
As for my suspension mods: My car is set-up by a racer who knows what he's doing. It's very neutral and done right. There is no way any stock suspension 3-series is going to hang with me in the corners. Also, the suspension reacts so much quicker than stock. My car soaks up bumps that sent my stock suspension drifting and shuttering sideways. Coming into this car vs. my Z06 is like night and day. The Z06 is a live wire that is just waiting for oversteer. You had to be VERY patient with the throttle coming out of corners due to the instant torque available to break the rear wheels loose. It did help rotate the car mid-corner though. By contrast, my suspension is set-up a little conservative to push slightly through the corners (i.e. safe) so I don't loose the back end, but ends up being very neutral and easily modulated (I need an LSD to play with balance better during cornering).
I also want to point out the fact that my instructor said that I am actually going as quickly as he was on the track. I looked over at his speedo when we were on the track in the instructor's group and he said "it doesn't feel as though we're going any faster in my car does it? That's because we're not." He has an e36 M3 with PSS9's on it.
So, to point out the fact that I don't know what I'm doing just because I've only had the car a short amount of time (a few track days too) and you've never driven with me is ridiculous.