I put in a Hot Rod Air unit in first, man I hated that thing, tech support sucked, they said it worked in my truck but didn't, parts missing, took 6 weeks to get my controller back from them upgrading it, and it still wasn't right then had to send it back, they wouldn't call me back, oh yea and the unit sucked too.
I then went with an Old Air system it works great, I agree with 235, it starts to loose something around 100. but that's Texas for you.