I've heard that chirp, but only on the twin cam. never heard an evo chirp. my 09 just started to do that with v & h classics. If you repack the baffle it should stop, or put a supertrapp they don't chirp

 

Entirely true, Ive had all kinds of mufflers on Evos and Shovels and never a weird sound out of them. I tried everything on this 04 model Dresser. I installed them of course with new rubbers, well lubricated. That is a bi-yearly maintenance requirement. I fiddled with the baffles, changing the air flow, wrapping them in different types of packing material, changing the tightness of the wrapping material on the baffle, tried 4 kinds of mufflers. The dual headpipes fixed 90% of the noise. I can still hear it standing next to the bike, but not on it while riding. You'd think a sound engineer at one of these muffler companies would have addressed this by now, there are alot of complaints on the various forums.

 

lets see the company try and patten that un-harley sound......right now it's not bad, but I'll have to do something if it gets worst. super traps and another tune

 

I have to spray a little silicone in the rubber isolators on the rear of the mufflers about every 3-4k miles...