Last night I put a Heelclicker HC-X Secondary Kit in my F7!!! All I have to say is WOW!!!!!!! The guy that put it in also has a F7 but he has the clicker weights in his primary and not the HC-X, and there is no comparison between my sled and his!!!! The power is soo even and pulls all the way through just like before when stock, but a lot harder!!!! I believe that this is the way to go!!!!! Smoked a ZR 800 EFI with Heelclicker weights, and a Mountain Cat 8000 EFI with a 151" track on about 2 inches of snow in 500'