Hi Len:
Exhaust systems make a big big difference in jetting, torque & HP. These engines are VERY sensitive to header diameter, length, and secondary lengths.
What do you have for headers? Did you simply bolt the Supertrapps to the collectors?
IMHO, Supertrapps do not work anywhere near as well as a proper race muffler system incorporating a crossover (dual-inlet mufflers do qualify) and individual mufflers on carbureted engines result in AFR curves that are far from being linear. If you retain the Supertrapps (with sufficient discs to make power, I would strongly suggest a crossover tube.
I would need to know your current venturi size to offer any jetting suggestions.
