Yamaha generously supplied me with a Yoshimura slip-on muffler to try, which slides onto the exit of the catalytic converter “breadbox” slung under the R1. First thing’s first, this Yosh pipe is gorgeous. It’s carbon-fiber perfection, in the classic Yoshimura shape—nice enough to spice up any machine. Since both the stock muffler and the Yosh one were in hand, I weighed each on our shipping scale here at the office. The carbon fiber and stainless steel Yoshimura slip-on weighed in at 4.1 pounds, and the titanium muffler from the stock R1 tipped the scale at 2.2 pounds. Then we spun up the Dyno and tested, via a handful of runs, each muffler in place to see if there was a difference in power output. There was no difference. Big thumbs down for Yoshimura, right? Well, no, not really.