sawzall.
Seriously, narrow bars are easy, just cut them down.
FYI, if you swap, I've found that moto bars have a wider "riser" portion, so you're forced to tun them wider than stock.
If you want to narrow stock bars significantly, you can relocate the controls, get a racer throttle block, and you'll be able to go WAY in. With the stock throttle you can go a little narrower, then you can hog out the inside of the block to allow for the downcurve... then you have to stop.
on a cat, for narrow I feel the stock bars are best.
If you needed to go narrower & weren't willing to do a racer block, a pair of straight bars would allow for more yet, but now you've got a system with ZERO give (like the mentally challenged engineers gave the 2012) which will cause issues of it's own.
