Both the T6's and T5's are a top end pipe...Depending on your type of riding you should spend a lot time considering this choice. The pipe puts the power where YOU want it. If you do a lot of tight woods riding w/ minimal top end, then get the 2 into 1 pipe. If you ride fast trail, mx, sand pits, all around, then get a midrange pipe like Pt mids, fmf gnarlies, fmf ssts, Bills, dmc. If you want to do some dune riding, fast tt racing, ice racing, drag racing then get some high rev pipes, like Toomey, pc, trinity, cpi, shearers, rockets, etc...