No way that boat runs 90mph w/575’s. I had one with 750’s and the best it ran was 88mph. They are great fun boats though. Wet ride in rough seas with wind to the beam.
It varies, but commonly water-cooled exhaust manifolds, water to water heat exchanger, back when they had carburetors that was changed a bit, spark arrestors on the alternator and distributor; brass, stainless, or rubber core plugs.
