Jason,
First let me say, I'm a fan of the GTS mustangs. Was keeping an
eye out for one, but got a sweet deal on the '97.
Did you get your blower direct from ATI? If you went through a store or catalouge, start with them. Try and return the unit as defective.
If you went directly through ATI, and don't get satisfaction, request to talk to a supervisor or service manager. Let them know you are upset, and will contact the better buisness bureau in their state. Trust me, buisnesses don't like getting a bad rep from them. Enough and they can lose a retail license.
There is good feedback available around here, even from people who don't have exactly the same setup as you. One of the best people to talk to here, doesn't even have a Mustang. Doesn't mean he doesn't understand them. Personally, if you only want info from people who have what you do, good luck finding a mechanic.
Just sit back, relax and get to know the board. I saw Capri warned you about language, and I'd hate to see you get banned 'cuz this is the place to be. Welcome, and good luck with ATI.
By the way, the 'Performance Industry' board was set up for just this kind of problem. Might be better dropped in there next time, although the response is a little slower.