I had a 06 YZ250F and now bought a 07 450F. The engine sounds a little different. more thump and maybe even a little more of a chain sound when letting off the gas. I could just be over analyzing aswell. The noise is something I really have to listen to hear. Is this normal? The thing is crazy compared to the 250 and doesnt seem to lack any power. Any experience with this? Someone who has gone from one to the other would be a great asset for advice. Thanks.