I'd keep the boost low till you get experienced with a supercharger combo. You can only shove so much air through a restricted engine. I almost toasted a cobra with a 14# ATI, edelbrock heads and an overcammed engine. All I have is a 6# blower with nice exhaust and 4:10 gears. Point is,start with the six pound system. Run your car then document it. Then tune and tweak everything till you get it to run the highest mph. Then try the larger throttle bodies, MAF meters, and injectors, so forth... One thing at a time. Then when that thing runs the best, and it's tuned perfect, try more boost. You'd be surprised how much power the base kit will give you. And don't worry, the A-trim is plenty loud.
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92 GT, 4:10 gears, centerforce clutch, 6# powerdyne blower, bbk h-pipe, flowmasters