I have a Slimline Pitts muffler, never used, but has a "dent" in it where it used to hit the carburetor. If you want it, I'll sell it for $50.00 shipped.

The stock muffler may fit but needs an extension of some sort.

I sometimes paint some white glue in the tank compartment, but usually depend on the assembly of the tank to keep things dry.

Yes, the hinge slots are nowhere deep enough. Lots of digging to get them cleared out. The hardwood trailing edge doubler on the stab didn't make it any easier either.

I used Pacer Hinge Glue on my hinges. Works just fine and water clean-up.