Huh, I thought Grab-A-Trak was a mustang's plus brand. Well in that case, I ordered pretty much that exact kit. I love it, I have muchh more control over the car now, and having the body roll went from a twice a minute thing to something very difficult to pull off upon even fairly aggressive driving. The only differences in my kit were the thicker sway bar and the 5-mid eye rear springs. As far as stance is concerned, My rear is about an inch higher than my front, but I also did the Shelby drop, which I highly recommend while your doing the springs anyway.
Installation isn't bad at all, took me and my dad about three days total, and that was with about a full day on just the coil springs. No real special tools are needed with the exception of a spring compressor.
If you want performance instead of a stock replacement, go with this over pick and pull.