The Thunderheader works and sounds great on my bike but the finish is not so good. Now the road rage has all three going for it and that will be my next buy. The D&D IMHO has a strange hollow sound until you rev it.
So far I think this is mostly a popularity contest - not what's best....
Interesting no mention of the R&B racing LSI/pro pipe series. Being their history I would put them pretty high for the performance results. Results don't lie...
I've never been a fan of 2-1s but I have my first one on order from RB Racing. I will find out what differance it makes over the stock head pipes with Cycle Shack slip ons that I'm making 87.5 hp / 97 tq. with.
Billy