If I change my stock touring exhausts, its seems I have a choice of mufflers ranging from 3 inches to 4 inches. What difference does the size make? Does a larger size equate to more power, more sound, both? I was going to call one of the manufacturers, but I figured I'd give you guys a try

 

Exhaust size means...........Squat! A larger size exhaust doesn't necessarily mean more power or more sound. It's all about the tune that is on the motor and whether the headpipe has been changed out. The sound of the exhaust is all relevant as to what you think it should be. Some 3" exhausts can be louder than some 4" pipes and vice versa. Some 3" pipes will give a little more power than a 4" will and vice versa. If I were you I'd hold off until you can go to a bike night in your area or go and hang out at Laconia for a day or two and give a listen and ask some questions if you hear/see something that interests you.

 

Generally*, the larger diameter of the muffler, the deeper and quieter the exhaust note. That being said you can have large diameter mufflers that are louder (and deeper) that smaller diameter mufflers; but comparing apples to apples, the larger diameter muffler will have a deeper and usually quieter note...