Check M109riders.com
There is a video including sound clips of someone drilling 8 - 3/8" holes in each pipe.
Since they have the same exhaust, same effect.
The more miles I put on mine, the more I like the sound. It's not obnoxious loud, but not whisper quiet either.
I know when I bought the 109 the sales guy was telling me that V&H has some exhaust system that boosts the HP to equalize having 2000cc. With the TRE, I'm more than happy with the boost I've got!
Hell, a cruiser that can compete with my buddy's Ninja is alright by me!