So chiming in, where I am not an expert as Matt is, I like to dabble a bit.
In terms of tires...I recently went with the Team Dynamic 15x8 F and 17x9 rear running 225s in the front and 255s in the rear. I had a little rubbing on wheel liners, but scissors helped...A LOT!!!
We are running Hankook RS3 V2s currently, and honestly they work well and fit VERY nicely with that wheel package. Wheels are from BWR. I also have the BWR Hardcore bar and the Penske D/A suspension package (500/700 spring rates), and after taking the year to get the car to set up properly...I think we are finally there with it. Drove this last weekend and it was awesome. Ironically my TPs are 22/24 (f/r) respectively.
We had a little chatter on mid corner in the front end, and after reading through this thread, I agree with matt, I need to increase my front camber as well, it is currently at -2.0/-2.1 and so I am going to pull a couple of shims as I think it will seriously help the car plant the front end a lot better on street tires.
Either way, long story short, welcome to the club of fun.
I realized this last weekend myself, that I am not going to be nearly as competitive as I want to be because I just don't have the funds. So I am going to take a year off next year and get my car build finished and then come back the next year and just have a lot of fun.
But I want to keep reading on the changes you are going to do to your car...and chime in where I feel like I can.
BTW, I have the BWR Hardcore bar, and on it, if you stiffen it, it cause the car to push more...assuming that your suspension is properly placed and well balanced at some point. Which in my case...we FINALLY got it to do that this weekend. My front end has been working SO WELL, that we couldn't figure out a way to tame the rear...without adding a spoiler to the back end like Matt's.
Dallasreed: Are those vents you were talking about the ones I sent you drawing for? Love to see what you ended up with.