I run mine 34 in the rears and 36-38 up front on my stock 235 18" tires. I remove the spare tire that's about the only "set up" I do/have done to mine. It will take some getting used to coming from a 328, but once you get used to it and know how to control it right it is actually a pretty competitive car in auto x. I found myself doing much better than I thought a heavy, high mustang could do. One of the things I like is how forgiving it is when the back end steps out. I have watched several of the lower/stiffer suspension cars (S2000's, etc.) get a little sideways and end up spinning completely on almost every run.
I'm sure you won't have any problems since you've been doing it for 8 years. Last year was my first year auto x'ing and I can't wait for the season to start back!
Here's one of my vids to give you an idea...