need help-please look!

[pro-rider46]

i put a big gun rev box on my bike and when i first tried to kick it over it would kick back preety frecking hard. this worries me because i dont want to break my ankle or leg. i know that they do kick back sometimes but it does it almost everytime i try to kick it and i also just pulled of the header and cleaned it up and i put it back on and off the beginning of my short ride when i began to hammer on it (full throttle) it started to sputter and it did not do it at all after that

it is jsut running a little funny

any suggestions would be greatly, greatly aprreciated
thanks