Ninja250 gearmod info? (changed rear gearing)

[stillsearching]

Curious if anyone has a ninja 250, with a changed rear gearing for mileage... what i'm curious is what did the change cost (and was it simple like DIY or complicated needing special tools), and how did it affect the performance of the bike? Did you do a 0-60 test or 0-30 before and after?

Power actually is important for bike safety to get out of trouble, and where I am with hills i'm concerned how much of a hit i'd take for an already lightly powered bike.