I noticed that the person before me took the shelf out of the airbox on my 99 mxz 600. I'm figuring that's why I am jetted up from stock 280's to 360's. Whats the reason for gutting the airbox? Should I go buy a new airbox with a shelf and replace it? Is it normal to jet up this high? I noticed also that he moved the needle from the 4th hole from the stock setting of the third hole. Are these normal settings and should I put it back to stock? I trail ride very aggresive and race in 1000' . Just want to know if theres a more performance one way or the other.