I'm running Brockman Steel Packed mufflers on four of my Flatheads. You can contact Brackman and tell them the kind of sound you want out of your Flathead and they will build you mufflers. On my convertibles I run the shorter mufflers and on the '51 F-1 and the '53 F-100 Panel I run a bit longer muffler. I like my Flatheads to bark a bit when they are cold, mellow out at speed, and rap off when you let off of the gas...they do make sweet music...
