"Uncorking" in reference to the XR650R refers to several mods, re-jetting the ridiculously lean stock carb, replacing the restricted carb to cylinder sleeve, and modifying the airbox to increase flow, and yes, re-working or replacing the stock exhaust. It's not about noise, it's about performance. The modified exhaust is a little louder than stock, but not nearly as loud as some of the race pipes out there. I have a XR650R and it is uncorked and still not too obnoxious with a Big Gun exhaust on it.