Folks, other than the obvious hard bags, windshield and floorboards, I understand the Tourer has more low-end torque but less high-end HP. Are their elements of the motor that create this, or is is just a matter of tuning specs?
Assuming you're talking about the Touring and not the Tourer (which has the same specs as the Standard/Classic), yes its mainly tuning. There's probably a bit of loss in the slightly more restrictive exhaust of the Touring as well. Both tuning and exhaust limitations can be remedied.
Had me going. I thought the question was actually about he difference between a standard Classic (rather than Standard/Classic) and the Classic Tourer (rather than the Touring).
The cats on the R3T are located in the muffler housings. So, there is no 'cat eliminator'. And the drop in K&N replacement will yield very minimal results. Your best bet is a complete exhaust replacement, triple K&N's, and the appropriate tune. That will get you up to reasonable performance. For more, see Mr. Carpenter.
Optionally instead of triple K&N's which probably also means carving up the bear claw, there's the Ramair filter that fits under the claw.
Though frankly, all you have to do to a Touring to get it to work very very nicely is put in the derestricting tune by Power-tripp. That won't get it fully up to Roadster level of grunt but it's much closer. +30 horses and +10 in torque and the ability to rev cleanly to 6k is nice.