I put a set of Brodix Heads on my 2001 500EFI and picked up 400 RPMS. We did not Dyno the motors but had a good base line on RPMS in boat. We did port match the intake to heads bowls were ported ( NOT MUCH ) cleaned up the Intake runners. We did reflash the ECU, very little on fuel and added a few RPMS to the rev limiter depending on what prop I would be using. Also saves a little weight on the tail end.