Just installed the heavier Yamaha flywheel on my 06 450. This is what I needed all along. I only ride off-road and the bike was kinda stall prone in certain situations. Much less so now. I was worried it would rev too slow but that is not the case. I have the Zip-Ty carb mod on my bike as well and the throttle response is still amazing, just less likely to stall in slow sections. I like this 100 times better than the Rekluse I had on for a little while and it only cost 104 dollars.