I know this topic is regularly beaten to death, but I have a 2000 400 ex and all I have is a uni filter with stock exhaust. The previous owner tells me it has a bigger piston in it but can't remember what it is? Lol. So I'm wondering if it needs to be jetted at all I plan on going to tall pines in new York in a week and there is lots of mud so I want to run the air box lid. Is it safe to keep it the way it is with stock jets or should I go up at all?