I put Superbars on my America about 4 years ago, no problems like you describe. I later changed the clutch cable for a shorter Speedy one because the longer stock one had an extra curve in it. I got the Speedy throttle cables, but they've been sitting on a shelf for a couple of years now. I'll change them one of these days.
Can you still see with the stock mirrors? I put bar end mirrors on mine.
