I agree BDI, good info there. My KX5 is pretty modified ie porting, head rechambered, NOS nitrous, and pvl ignition. The idea of the reed spacer has been tooling around in my mind but never did use it because I didnt want to loose any top-end. I've been debating between the V-Force and Rad Valve cages and by all the replies using the search sounds like the v-force is the way to go. I have been using stock for the longest time and have been happy with them but I like to tinker for more hp but at the same time I really despise spending money on a product that doesn't perform the way I am hoping.