You may be feeling too much rear suspension pre-load and/or not enough spring effect from your rear tire.
You can play with both and see what combination improves your riding feeling.
If your rear shock doesn't bottom up frequently, and if you don't ride two-up, you can safely experiment with less pre-load.
If you do, and are happy with the result, recalibrate the height of your headlight beam.
The manufacturer's tire pressure recommendation is just a starting point that works for most riders, you could be an exception due to your weight and riding posture.
I have the feeling that you could lower that rear pressure some if you use temperature of the carcase as the limit for low pressure.
These threads explain more:
http://www.ninjette.org/forums/showt...=tire+pressure
http://www.ninjette.org/forums/showt...699#post737699
The way it is now, you may suffer some rear chattering and side-walk when leaning hard on crappy road surface.