I put a new set of 3.5' Scalloped Python slip-on mufflers on my Roadking a few days ago. I previously had an old pair of 4" VH Classics on that were old with chrome peeling off the end-caps . The difference in the power curve was significant so I thought I would bring it up. The tone was way different which what I really was going for, the Pythons are less "barky", more tuned sounding. What surprised me was the performance gain in the low to mid-range, but losing some top-end torque that I had with the 4"VH's. I ordered the optional "competition" baffels for the new Pythons and hoping to spread the power band upward.

 

A few things with baffles can affect performance. Things like diameter, length and probably the louvers/flap looking things. I experimented once and put different diameter and length baffles and no baffles at all and found different results performance wise with each.