Muffler Options?

[Tom Y]

Anyone still looking I have a Nelson muffler 5" in and out. But shipping would be $$$. If the muffler you removed is a Catalytic it may have some value, the cats from some cars have a good junk value.

[Jim Eh.]

Good to hear. The old system could cause the panels to warm up more because of proximity to the panel (size) or because it is an offset design (looks like from here) which creates more heat requiring the "double wrap" in the first place but having limited success. If the straight(er) through design of the Donaldson vertical muffler runs cooler then no worries. Enjoy the fuel/power benefits and the hot rod sound.  
Nice KISS installation.

Can't find a picture of a diffuser but have a look at the "twin" tip of a late model Ford 3/4T Super Duty there are small "flaps" bent in to create a venturi to draw in atmospheric air to mix with the exhaust gases. This does two things, reduces the exhaust outlet temp significantly and dilutes the exhaust much the way the 70s-80s cars used an air pump to meet then current emission standards.