With the Steeda stuff you should be fine. Its as competitive or as laidback as you want it to be. I got into it last year, and sure there are tons of better handling cars out there, but I still had a blast. With your suspension and the power your making you should do very well. BTW - Event the first couple times when I didn't drive that well it was still insanely fun! BTW go-stang5.0, feel free to send me an email if you just want more general info or if you have anymore specific questions.
Also, I should have worded the questions better, I won't be changing my oil just for Auto-X, I just wanted something that will hold up well to that abuse and be OK on the street. I disagree that my car will see more abuse on the street. I beat the s*** out of it at SCCA, and I have too many speeding tickets to drive like that on the street!