I ran a thread on this with mixed replies.
On my 98 wide glide and my Buell s2, as you turn the throttle the rpm increase........(with as little as a 1/16" or less turn).
The TBW , on my 09 RK has at least 1/4 inch of "nothing happening" slack as you turn the twist grip.
Dealer says no cure.........(it is a mechanical thing between the 2 gears in the control)
The response is great, especially after Reinhearts, SE filter and a remap...........(it was acceptable before)........but the "slack" is still there...........(just like a throttle cable that has stretched).
2 different things.....(I think).........response and free movement of the twist grip with no response from the engine............"slack".
The dealer says "you will get used to it.......as others have also said the same.
Just my $.002