Anyone know anything about Vortex mufflers?

I'm back from Iraq and visiting my mother in upstate NY. I already put on Bils and AAL's and want to get a performace muffler. As I call around to local shops asking about the Flowmaster 40 none of them carry it. However, a good chunck of them carry the Vortex. They are telling me it is comprable to the flowmasters. Any opinions? Another thread on XOC mentioned they hold up better to the rock salt. Could that be why these shops carry it instead?

I just had the Flowmaster 40 Delta installed. I was able to track one down in the local area.