For those using the Jtec Wrap Around Pitts Muffler and having some problems,I did some mods on my JTec Wrap around Pitts Muffler on my TF P-40 after reading about them coming loose; I welded braces on the muffler, drilled holes in the bolt heads and used wire and also used Dynathrust washers instead of the split locking washers; here are some photos of the welding mods, 2nd picture does not show the wires on the bolts, those were put on after I ran the motor and warmed up eveything and retightened the bolts
The way I figure it, without providing support to the unsupported end of the canister allows excessive vibration and shaking, which causes the muffler to come loose or even crack, not clearly shown is an additional brace I welded across the 2 tail pipes to keep them from shaking independantly.