[MOHillbilly]

The big improvement comes with the fuel tuning, especially in the midrange. The factories map them so lean in the mid to pass emissions, that they're barely running. As a rule, you don't gain all that much on top end power, but can see 5-6hp in the mid range. Plus you get a much smoother, better running bike all across the board once you get the A/F at 13.5:1, no matter what exhaust you have.

 

[MOHillbilly]

Hmm is it ok to reflash ECU on the stock air filter? or should I replace it with a performance fiilter

Intake system on most bikes makes very little to no difference in performance. K&N or OEM paper filter, doubtful you would see any change on a dyno. But, with that being said, a gauze filter won't hurt anything. Have a K&N in mine.