Thanks RobH for this quick answer, but i saw all links and topic about derestriction...

My question was more about how a restricted Nsr drive like, how fast and whats the difference, is the power cut in some high rev?

For example a restricted nsr50 go to 60km/h and 8000trs/m when derestricted go to 90km/h 11000trs/m its just an example

Unfortunally there are no shop with dyno in the place i live even no decent motorbike shops actually

i think you right i should get a box like m max or Kiss and plug it see if there is any difference...