Yea, I dont know what the hell they were talking about in the Kawasaki forum but gas pressure build up in the fuel tank is not a good thing...I had a lot of gas pressure build up in my fuel tank, the pressure nearly blew my hat off each time un-screwed the gas cap....The problem was that the venting hose from my new gas cap base had a kink, i fixed it , now there is no more gas pressure build up or any of that hissing noise.
I can't believe i thought that it was normal for gas pressure build up in the tank, Its Not..