I have always been a fan of Donaldson mufflers performance, but they are a little too quiet for me. I am going to try a M090072 resonator/muffler. Most guys seem to run this with another Donaldson muffler, but not just the resonator. My hopes are it will still have the 5" straight pipe bark and a little less drone all for about $60. I'll let everyone know how it turns out.