I had some of the same concerns, so I called a number of dealerships and got a different answer from everyone giving me no help at all. At the end, I decided to leave the stock Harley headers and go with Rinehart slipons. It produces a bit more TQ and a bit lessHP in the numbers, but I figure that TQ fills the seat of the pants o' meter better than higher RPM HP does.That left me with quietersound and over heating.I can tell thatmy exhaust is a very smallamount less than some of the more open exhausts buthas a verynice deep sound and a good bit of openness still. I love the sound. With the SERT, they were able to get rid of the overly lean stock condition that makes it run soooooohot. I also spent the money I would have used to install the true duals over the slip ons (slip ons are <$500 and true duals are <$850) and bought the HD performance oil cooler. It comes with a chrome cover and looks sweet down there. Bike runs cool and nice and IMHO puts down plenty of torque with a good sound.