I called VTXexhaust & spoke with Bill. He was very nice to talk to & extremely helpful. I gave him my spill & asked if he knew whether or not the VTXexhaust modified mufflers would lower the header/engine heat retention. He told me that although they have not actually done a "test" to prove that it is so, he could tell a major difference in heat retention once a set of their exhaust has been installed. He also informed me that the stock muffler has 3 compartments seperated by 3 baffles which is the main cause of the heat retention. A VTXexhaust muffler has only 1 compartment with a "tumble" style supressor which allows the air to escape through a 2" (1300) or 2 1/4" (1800) opening. Given the information Bill gave me & the price Vs an aftermarket setup, I'm thinking I found a solution to my problem.