On my boat with the V1 muffler I have to go 1/4 turn leaner and its down 2 - 3 mph. V2 muffler 1/4 richer and 2- 3 mph faster. Switching heads made no difference
however my water cooled head was restricted.
There is More RPM in the V2 Muffler. I have tested back to back to back to back and...