D&D does NOT give more performance at all. If anything, the lower backpressure takes away your low to mid range power. They're just loud, annoying pipes.
Most pipes won't give you that much power alone. Even with a PCIII and a proper map, you might get about 3-5hp.
Most R6 guys seem to like Micron or Yosh. I like my Yosh but the Termi is nice too. Check out
www.solomotoparts.com. They have pretty good selection and the online guy is a R6 rider.