MT, here's a different idea for you. It would be nice to be able to quantify the results of modifications you make to your car. Why not get one of the electronic testing units like the
G-Tech first so you could do a baseline on your car. You could then run secondary tests every time you make a mod and be able to see what differences the mod made.
The second thing I'd get would be a tuner,
XCal2 or
Predator. I personally favor the XCal2, but it really comes down to which interface you prefer, what you think of the additional features like data logging on the XCal2 and local support (unless you buy the tuner by mail)
WRT the buying a tuner in general and the XCal2 specifically, do some comparison shopping, not all SCT dealers provide the same stuff. Make sure you get all three tunes (87, 91 and 93 octane). The first local shop I went to wanted to give me just one tune then charge me $100 for each additional tune. I got my XCal2 by shopping the Internet and buying from a tuner in a different state (
VMPTuning) who included all three tunes and was recommended by SCT as having great customer service. I have not been disappointed.