First, just let me say this is my own personal experience and I am far from being an expert... I am only on my 3rd HD. My 1st was an XL1200R which I put a set of Cycle Shack slip ons that looked almost identical to the stock HD mufflers while my wife went with the SE slips-ons. I think my bike sounded MUCH better and performance wise my bike would just plain walk away from hers (and get better mileage too). My 2nd HD was an 09 FatBob and I went with the SE slip-ons because they look really neat. VERY disappointed with them. Vey quiet and almost no gain in performance. Bit the bullet and bought a pair of 2 1/2 inch slip ons from Cycle Shack and loved them. The bike actually gained 8 MPH top end and just plain ran better, plus they sound fantastic. My new 2010 UC Limited has the cats in thre headpipes, so basically was forced to buy a complete system and went with V&H Pro Pipe 2 into 1. I listened to a set of them on a softtail last summer and I think they are the perfect balance of sound (and what I am told performance wise). I have a nice set of SE slip ons for FatBob/2010 Wide Glide with holes in the baffles if anyone is interested. They are still too quiet even with holes in the baffles. The previous advice about listening to bikes at a rally and deciding what you want is fantastic advice. For overall sound, price and performance, I think Cycle Shack muffles are very hard to beat though.