Ford racing performance dual exhaust?

i have a 2006 v6 mustang and im looking at getting the ford racing performace exhaust, but ive been hearing a lot about GTA. where can i find those. ive looked up gt take offs and havent found anything. if you could post a link or tell me a little more about them id really appreciate it. and also if you know where the frpp exhaust is the cheapest feeel free to inform me. thank you.