If you run with no lid at all, you will be changing or cleaning your filter before a whole day of riding. Especially in dusty areas. No lid does flow more air, but you need to increase fuel to get the full benefit from it, like with a Power Commander. I went with these guys. They modify a lid, complete with filter material, ready to bolt on. This cover is almost waterproof and keeps the inside of the airbox much cleaner. WWW.EHSracing.com
