There’s no head to shave which y’all are all used to but merc did is a favor and in 1989 redesigned the combustion chamber to be swapped out with older 25xd pistons to run 200 psi. There are also windows to get to transfers. There’s a big void behind the reed block that needs to be packed with marine Tex to up the crankcase pressure. adding a spacer in between the water jacket isolation cover on the exhaust side as well as cutting the exhaust tuner to 4 inches long. Widthen the exhaust port don’t raise it since it’s only 18ci. It will pull an 18p chopper 7k in a light inflatable
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