I have a 2000 400ex. I was wondering how much difference the 440 kit really makes. my quad is still stock, I rode a friend's this weekend that had a fmf megamax and I couldn't tell much difference. I'm sure the kit makes a difference, but how much?

bigfeet

 

the kit is like 285 retail. then you have to pay someone to bore out your cylinder and resleeve it. you also have to pay for teardown and reinstall of the top end unless you know how to do it yourself.

 

The IMS kit by itself makes a noticeable difference, especially on the bottom end. However, if your EX is stock I suggest looking into pipes, air filters, jet kits, rev limiters, even just a stock bore high compression piston before you jump right into the engine work and cost of the 440 kit. I know from experience that the 440 kit doesn't show its true potential without a cam and even a bigger carb and head work. you definently should have a pipe, filter, etc... before you do the 440 kit and what goes along with it. My EX really rips now though!!!

 

Just the 440 kit alone will not help much. You need to have a complete engine. If you arent going to do it all at once, then start out with the bolt ons.