At what RPM's should I be shifting the ninja 250?

The person that had it before me changed the mufflers to the"Two Brother's"mufflers and are so loud. With other bikes, I used to be able to tell when to shift; however, with these mufflers being loud, I can't tell when I should be shifting to a high speed. Or even a lower speed it all sounds the same to me(loud). Can some tell me with their experience, at what RPM they usually shift.

Oscar its a hard call on a high reving'low torque engine. Mostly its by feel and whether you are accelerating or crusing. Youll be a lot happier if you go to the original owner and get back the stock muffler ( so will the neighbors).

you could always just change the mufflers back to what ever they were beforeother then that, i dont really know