CES header pic below (the muffler isn't the CES muffler).
The lowest pitch pipes in my opinion are the Jardines, but it still sounds nothing like a 270 degree twin. They're a bit tough to find these days sadly as the Jardines aren't made any more. They sound really really good though. Not loud by HD standard, fairly loud by Rocket standards. The tone is M U C H deeper than any I've heard on other R3s, the cans on them resonate the right frequencies and block the higher pitched ones.
The Carpenter pipe is also deep, but its a raw sound. If you've ever heard an SRT-4 with no cat, 3" exhaust, into a straight through muffler, its pretty much just like that, personally i like it
CES and Reband don't sound deep in my opinion. There's the underlying deep tone you cannot avoid with a 4" piston, but, the dominant sound isn't low low pitch. They sound like what they are, a massive bore multi cylinder motor.
Regarding tune, it's very, very simple, and the only thing you have to have are a laptop and a $20 cable, see video 3 here:
Random Tech thoughts vlog as related to Rockets
What is sounds like off the bike:
Sound on the bike (mostly induction noise):