Installed on a YZ250F. Loads of power. Was able to keep up with 450s. Easy to install. Use the circa clips provided by Athena. I made the dumb mistake by listening to a earlier review by using stock circa clips but they came out and ruined my cylinder and piston. Use Athena's. They do extensive R&D with their products to include their clips. Wasn't Athena's fault at all. All my own. Got the new (discounted) kit in there and I'm back to full power. Of course do a valve adjustment with the swap for optimal power. Now I do have hot cams so my power is extensive.