[mr2silvertop]

Riding in high gear on low rpm will get better mileage but fouls plugs faster. I mean you don't want to ride around going under 2500 RPMs. You'll get alot better mileage if you use 5th gear when going 55+. Of course you won't sound like you're destoying your engine.As for the sound, is it when you are slowing down? It may be the tranny whining.