PM 96 Goldbird and ask him how much he is paying for Scott to build his tbird. you'll piss yourself. But they are doing it right.
AED : Usable on stock motor, will see 260-325 at the rear depending on mods.
Vortech : Usable on stock motor, will see 325-380, motor won't last long
SVO : same as AED
KB : Insane gains on forged internals.
AED/SVO are roots blowers. This means low end tq, top end not as good.
Vortech is a centrifugal. This is a blower that sits outside the motor and is belt driven, the different Trims are the different packages like intercoolers etc.
KB is a twin screw blower, it will get you power at all ranges.
Expect to spend $3,000 just for the blower and parts, and if you want the motor to last or take more than 6 psi, add at least another $1500-$3000 for that area.
Then you'll get into the trans, SCT tuning, and it will cost even more