Got my TT BBC out to the lake last week and she's running strong. With a HTP built jet throwing a AA Heli Stainless with cavitation reducer, its only turning 5200 RPM. Had the engine dynoed at 4300 feet making 649 actuall HP at 4900 Rpm and peaking at at 667 at 5500 RPm. The HP stays very flat from 4900 to 5700 plus or minus 5 HP. My question is should I get my impeller cut for the extra RPM and would I gain more MPH, or bump the boost up 2-3 psi from 12 to compensate for the 5100 feet my lake is at, or leave her alone to live a long and prosperous life.