I like the looks of the Klock Werks Double-Back system... But I can't see how it would reduce the HEAT in fact I would think it would increase the heat to the rider on '07s and up. Rineharts TD they look good and sound good but I haven't had much luck with them on my '01 RKC - Replaced 3 Mufflers (Baffles broke loose) 2 rear header pipes & 3 sets of tips.. My son's '05 RK had failures also. You do know you will loose a little performance on the low end with duels, but not that much.
That's why I did the Bub 7 TD with crossover and they are great!
Rhinehart TDs here. Great quality, nice sound - a little pricey but worth it. I noticed a reduction in low end torque so I bumped up to 103 - now its really loud and has plenty of umph.