If you take off the Lid youy ahould put a high-flow filter in there like a K&N and then you will feel and hear the difference my airbox is louder than my exhaust.

 

that's a pretty sad exhuast...lol
j/p [img]i/expressions/face-icon-small-cool.gif[/img]

 

yellow o3 400ex w/ 14 tooth front sprocket and a white bros. e-series are the only mods.....so bigger jets are needed for a higher flowin air filter?i know they use negitive air pressure to pull gas thru the carb. thats why they bog from being to lean...........whats a good jet kit and what size should i use?

 

Crispy hav u ever heard a 250ex stock exhaust its pretty quiet.

 

if your only mod is a slip on, i would put in a keihin 152 mainjet. don't buy the jet kit, they are a waste of money.

 

ya