Without a Tachometer, How can I tell if I am pushing the eng

[Nightsbane]

...ine too hard?

This is my first motorcycle, so I am not totally intuned to the sounds, and I am about to have to start driving to class in a couple weeks on a 55mph highway. When I head out to 45-50 mph it still sounds much louder/higher pitched than usual, and I don't have any clue if and when I would be pushing the motor.

In town I usually shift at

2nd after roll
3rd at 20
4th at 28

and 5th at 35+

It seems to run better at anything over 35 in 5th, is that correct? I am six foot and 200 pounds to gauge height/weight. I just don't want to blow it to pieces this fall. Also any highway driving tips on this bike at those speeds would be appreciated.