I just had a Vortech S-Trim installed on my '00 GT. All I gotta say is it is awsome! Shocking increase in power, it's great. I have 30k miles on the car when installed and I wish I had put it on sooner. I had it installed in a speed shop in Orlando, FL, Powered By Ford. Real professionals they were great. Try the following website for your research on superchargers, they're a bit Vortech biased, but have excellent info on superchargers.
http://www.motorsportsdigest.com/tech.htm