last night i installed the 42t rear sprocket (did not have to shorten chain), 1 inch bar risers, and 2 inch rear lowering links. i am going to wait about installing the 15t front sprocket to see how good i like the 14/42 setup first. if i like it i may just save my 15t front sprocket until my next chain and then try the 15/45 setup for comparison. i have a feeling that the difference between 14/42 and 15/45 will be nonexistent, especially since the ratios are exactly identical at 3.00, but we will see.
i have never had the older ninja for comparison, but i bet the mechanics are pretty similar, atleast the engine. the cams are different, and maybe the carb settings, but thats about it. but from everything i have read, the older ninja 250s are ultra-reliable, and super-efficient. or atleast they are when people aren't trying to ride them into the ground
. but the new ninja 250s should be just as reliable, i would think.