The mighty Yamaha YZ450F is practically all new for 2023 and ready to inspire new MX champions everywhere.Lets get right to it ... the stock system on the Yamaha YZ450F was hard to improve, but Yoshimura did! The magic of the right tube diameter at the right length, then Yoshimura's RS-12 was called in to do the work that it was designed to do ... perform! Adding power and torque everywhere across the spectrum of the new YZ450 wasn't easy, but it was accomplished. Max HP is increased by 8% and max torque is bumped an incredible 13%!The new RS-12 system unlocked some key power in the right places. The lower and mid RPM range is really enhanced while not disrupting the handling characteristics on the new YZ chassis. Riding with this new added power really made testing the new system a fun project.Other highlights of the RS-12 system are the machined joints on the key tube junctions to insure a good clean interface between joints. A built in resonator chamber on the silencer, a matte carbon fibre end cap and a PTF low volume sound insert completes the RS-12.Spark arrestor sold separately.