I have a straight pipe on my CBR300R and it is without a doubt louder than my straight pipe R6 (no dB killer) and louder than my straight pipe CBR600 (no dB killer) and louder than my Screamin Eagle II HD Sportster 1200R. The sound volume of CBR300R is by far louder than all and it's obvious. Even my 124cc Grom with the dB insert out is crazy loud. What makes a single cylinder so dang awesomely loud?