On the 80-83 exhaust you can just get an extractor in place of the crossover.
It comes painted black.  After running it about 3 days all of the black will
burn off and now the extractor is almost full of surface rust.

What can be done BEFORE installing it to insure the rust stays at bay a good
while?

Paint it with super hi temp paint then bake it in the oven?

Funny the cheap Bugpack muffler has no rust though...

Paul
'82 Vanagon L Automatic