I'm not sure that changing your air intake silencer will do anything for you. The engine is already a supercharged engine. They have a high air flow volume so I would do nothing to restrict that.
If you want to toy around with the idea of high performance for your boat, I suggest you go to www.rivayamaha.com and search their high performance parts. You can order pump wedges, nozzle extensions or powernozzles. With the horsepower of your motor, I think you'd be better off with a pump mod than an engine mod.:cheers: