dizzle250

I have an 04 rmz250, and I recently thrashed my back sprocket and chain guide. Due to the flat top end I was thinking about re-gearing both sprockets to help up top but not sacrafice low and mid delivery. What are u guys running? 13/50? Plus I want better throttle response, should I change the stock jetting. Do any of you guys run a power now valve or a power shot in your carbs? Don't have the cash to pipe it! what to do!!! any advice would be greatly appreciated! thanks