Just the Mufflers Only !!!

I am looking for a louder sounding MUFFLER only for my 2006 stang GT..
I called Midus up and they will put on Flowmasters on for me at $350.
Unless you people think I I should buy another type of Muffler and have them put in in?
I don't want to go crazy and pay alot for 2 mufflers.
Will ONLY changing the Mufflers will make that much of a differance?
I am looking for a louder sound.And If I get flowmasters what ones would you all say I should get ...Thanks...............Thanks allll JohnnyT