I say they do pretty well. Pretty sure I gave up some top end horsepower but they perform well down low where a bagger needs it. There are some fitment issues with the 14's. Some bolt right up and some have clearance problems with the footrest.
I use the speedster duals with the powerport....... I love them, nice growl, and I don't get the stock heat. Equal output from both sides. Now these aren't the duals, but the powerport is the same.