Hi Sandie, one of the best things I ever put on my bike was a wind shield. For highway riding it made everything waaaaaaay more comfortable. If you ever had to scratch an itch on the highway without a wind shield, you'll know what I mean.
If your worried about damaging the engine by running too high of RPM's, you can use the speedometer as a guide. The red numbers labeled 1 through 5 are the max engine RPM's for that gear. If your in third, just don't let your speed go above the three. I you use this system you'll see just how high the engine revs can be. And Honda considers this all in the safe zone!
Personnally, I like to ride around 45 mph. Most of my riding is around 55. When no traffic is behind me I'll do 45.
I have the 30T sprocket on back and positively love it! But, like flite mentioned, on the highway, going up hill into a wind, I lose speed.

As I stated, most of my riding is at 55, so I think it suits my needs just fine.