To start the test I put everything back to stock with regard to fuel injection and ignition timing. On the track it didn't take long to understand the changes the Yosh exhaust made to the power curve. First and foremost is the top-end performance. Instead of going flat and signing off, the Yosh helps the power run a lot further up the ladder before tapering off. This alone helped fix the issues with second- to third-gear gaps. Now I was able to hold second further in the rpm range and shift deeper into the power curve going into third.Second, even with the stock ignition and fuel settings, the low-end is a lot smoother, which makes the bike easier to ride. It is almost as if the Yosh exhaust took over where the Yamaha Power Controller left off. And with the controller you have even more when it comes to tunability.The RS-4 puts out a nice note and is capable of getting down to 94 decibels with the optional AMA insert. With the insert installed we were not able to tell the difference between the two on the track. Looking like a piece of motorcycle art, the Yosh is not a cheap addition and, to some, a hard pill to swallow at nearly a grand. Yet in the end, I did not regret the purchase since I planned on keeping my 2010 for a second season, not to mention I am digging the newfound performance and ease of riding.