Hey Jack21, 
I got mine at Speed Unlimited up your way. Our local muffler shop has'em too here in St Augustine so they should be available lots of places.
They're made of fairly soft copper so they conform to the surfaces OK. What sold me on them was multiple reasons: the package said they use'em on AA FUEL cars (that would be more abuse than I'll ever give them), their coefficient of thermal expansion is closer to steel than the aluminum ones that failed, and I'd also blown out a set of the sandwich-type gaskets. So far the copper ones have given no problems after 10K+ miles of, um, testing.
Tom