This is a HP build, High compression pistons, 10:5 to 1 , hp camshaft, lightened flywheel, twin 40mm side draft webbers, should dyno out at 135HP, for the small cost I opted for a High volume pump, I needed a new pump anyway, the difference is the diameter of the pickup is 1/4 inch larger, and the length of the pump and housing is 1/4 longer, I'll post pictures soon of the 2...cheers