I never noticed any loss in performance; however, I didn't dyno the bike either. The true duals really opened up the left-side pipe, it is equally loud as the right side now (it wasn't before). I like the pipes, they perform well, look good (IMO) and most of all, not many people have them. I get asked all the time, "what pipes are those"? I like that.....nothing against the popular pipes but there are other nice choices out there that are not as common.