The Yoshimura RS-2pro and the Drd pipes have received excellent reviews from mxa and transworld(current issue) on the YZ450. If you are looking for more throttle response then both of these pipes would work for what you're after. I haven't seen a test on the WB pipe lately but they are also good pipes. Decide which you like at the price and buy it, you won't be dissapointed. There is no difference between the aluminum models and the ti/carbon models outside of a little weight and trick factor.