Originally Posted by
6X6
Jim, for low noise I don't really think going to a smaller engine will be a big benefit, or any at all. You'll be using more throttle, even with taller gearing, simply because you will need to turn more RPMs. I would recommend a sub-muffler. (Run a glass-pack muffler inline, before the main muffler.) Also, since the engine makes a good bit of noise that isn't coming out the exhaust, fiberglass engine bay insulation would help as well. Of course you can't close off vents, but if they're baffled so it's not quite a straight shot for the noise to escape, that should help a bit also. A bilge blower for a boat would help if you have too much decrease in ventilation flow My .02