Those speeds aren't doing it any good. It's only 800cc. If you want to run those speeds, I suggest you buy a DJ drive. It's a rear drive out of a VL1400 or 1500. It's a different gear range so it lowers your RPM's. I love mine and have been on a few trips of over 1000 miles at hiway speeds.
You know, perspective is an interesting thing. The first bike I actually owned was a 1982 Kawasaki 250 LTD -- 246cc, single cylinder, whopping 17hp and an enormous 2.1 gallon gas tank. The thing was a torture rack on wheels. The seat was a killer. And buzzy? After 30 minutes hands and feet went numb unless you constantly flexed and rotated them. It would hold about 75 at full throttle -- heck, I recall one day, no wind, full throttle, full-tuck, going juuust slightly downhill, I hit 90. Whoooweee!
But -- I was young and hearty, and I put 18500 miles on the danged thing in just 2 years, probably 2/3 of them on the Interstates, 100 miles between gas stops and 50 between butt-rest stops. The little bugger never faltered or failed, never burned a drop of oil. I ended up selling it to a county sheriff's deputy who retired recently. Ran in to him a few months ago and asked him about it. Amazingly, he still has it. It's still running, although it needs work (I bet!) and is not currently roadworthy, and he told me he's taught 3 grandchildren to ride on it. I asked if he'd sell it back to me -- no way. He said he has another grandkid about ready to ride.
Now my long-distance bike is my '08 C50. Compared to that Kawi, it is a veritable Rolls Royce. Everyone is entitled to his own opinion, but as far as I am concerned anyone who says 800cc is not enough for Interstate travel is, quite simply, wrong. It's not the fastest thing on the road, to be sure, but if you need 75-80 mph all day long, it'll do it without breaking a sweat. Will it break 100mph? I don't know. I have had it up to 90 a few times, and it was still putting out some pull, but who cares? 90's plenty fast for me, thanks. I ride solo, and wouldn't really care to double up on it with Big Mama plus luggage, but for me and my stuff -- plenty of poke to go around. As far as buzz, the only buzz I feel is just what you're going to get with any fairly decent-sized V-twin, and not nearly as bad as some.