those bars made your bike seem twitchier? You don't have the 2011 steamroller that came with the mustache bars, do you? That's what I bought, I switched out to risers two months ago and have slowly been shortening the ends. The original bars were ridiculous and definitely not anywhere near twitchy.

As Kayce said, the closer your hands are to the steer tube (assuming that's what it's called, still learning names), the twitchier the feel will be. Wider bars will feel smoother, narrower will give you less control.