I've got the same exhaust on my 636, and while I love it (looks and sound wise), it is loud as FUCK. The drone around 4-5k can get pretty bad, but you're right, at higher rpm's its not nearly as bad. Because of this I find myself cruising at higher rpm's than I probably normally would. I used to wear ear plugs, but not any more. The only time I do now is if I'm going on a really long ride/freeway ride. Completely forgot my point of this post haha. I've been followed by plenty of cops, and because of the exhaust my license plate is mounted sideways down by my tire...without a light. I know this is probably a bad idea, but it's how I bought the bike, and no cops have ever given me any kind of trouble.