I have see that the motocross racing bikes are all changing over to 4 stroke motors and they are quite a bit quieter than the old 2 strokes I used to race as a kid. Also the new outboard motors are all changing over to 4 stroke motors, they are very quiet and supposed to get much better gas mileage too. I would hope the Jet Ski's would be next to change over to 4 strokes and get rid of that never ending chain saw noise on the lake! Hopefully the 2 strokes will be outlawed pretty soon.