Just bought a CRF 450R. The bike had only been ridden 3 times prior to my acquisition. Rode for first time this weekend.. Love it! Still has the factory chain and sprocket set-up. Ride mostly trails and occasional track. Thinking of a sprocket change since I am going to a upgrade in chain(O-Ring). Has anyone tried a 13-51 setup. What are the performance characteristics. How many links do I go with if I choose this route. Will I loose too much top end. Ineed advice.