ive got a westcoast full pipe, ocean pro high compression 440 or 550 head it truly works on either the domes on this one are super small so ur looking at a ton of performance, copper head gasket, freestyle pump cone, pjs aluminum driveshaft (for a 550, id reccomend switching to a 550 pump and driveshaft anyway, the 440 pump puts all the pressure to the bulkhead, and when u mod the ski, u would have to get a bulkhead support which are hard to find, or just switch out to a 50 driveline and pump). ALSO LOOK FOR A BIGGER CARB!!! dont even think about modding that ski and keeping the old bn38. u need at least a rebuilt bn44. or even a intake spacer and spn44. anyway, it doesnt matter how much u mod the engine, if its not getting enough air, it doesnt mean anything. there is such a thing as too much air too. lol