What is your air filter/jetting? When I ditched the can stock it gained quite a bit of power.

I replaced the stock air filter with a gs500 hi flow air filter retaining the stock air box.
the jetting I'm not positive about yet. I was told it was jetted when I bought the bike but no details on it yet.http://i.ebayimg.com/00/s/MTA2NlgxNj...1-w~~60_57.JPG

Yep Same filter I installed in mine. ;) :)

Awesome,when I got mine stock I cut the can off and went from a struggle to 55 to 75 easily. Deff gotta get bigger sprocket the vibes are killer on the highway.

I tried a few different sprocket sizes and ended back at stock. I put brand new front and rear sprockets and chain on a few weeks ago. I don't have any vibration problems.

Really? My gz humms at anything over 65

Easy fix. Don't go over 65. The GZ will normally go faster than that but it won't like it.
In the real world the bike is geared for most riders and roads. It was never meant to be a freeway bike and competing with big bikes, cars and trucks.

I guess your right but I just can't see myself avoiding highways due to rattle, the bike has much more power than a city hopper.

That may be true but we had a rash of members with dropped valves which seemed to boil down to higher speeds and hotter engines. You have to keep in mind the GZ is a 3rd world bike. Made to be a workhorse and family limo rather than a racehorse.

I really wish I never learned that.