Remember the “less sound equals more ground” campaign of the 1970s? Bikes for use away from closed-course racing have to meet strict noise emissions, and with one big booming 450cc cylinder that won’t be easy. The old boom-box mufflers on 750cc flat-track racers only had to quiet 375cc cylinders. So no matter what muffler you design for this CRF450L, every other sound source on the bike will have to be studied, identified, and quieted as well. A quick phone call to the “Noise, Vibration, and Harshness” department brings a study team equipped with microphones, recorders, and analytical software.