The problem with jetting all of our engines for peak everything is that it leaves us way over jetted in low and midrange.  Adding a Dial-A-Jet allows you to reduce your main jet by three or four sizes, depending upon how rich you currently are.  Your machine will run much more aggressively in low and midrange.  You will have more power and better throttle response.   As you approach any or all of the peaks on the top end, the Dial-A-Jet will automatically meter out the correct amount of additional fuel needed to match those peaks.