They took out the stock baffles, replaced it with their own and then added the black end caps. I thought that it sounds great for a stock bike. I think that Fullsac Performance does pretty much the same thing.I saw some of it, was dozing in and out. Bike didn't sound all that bad, after baffles were out. Was there a black insert put in the end of the pipe, after baffles were taken out? I was snoozing off and on and didn't catch the second show about the H.D.Boots.(making of)