You wont get much louder than a stock muffler. Any straight thru design like a red cherry bomb or magnaflow tube muffler will give you louder sound. The tail pipe quiets down the sound a bit. And even worse, the Catalytic Converters quiet down MOST of the exhaust noise ( believe me.. hehe) . Unless you get an aftermarket H or X Pipe or gut the cats ( means knock all the crap out of the converters to make them hollow), you won't get much better sound than stock. Understand when I say this as this comes from someone who has owned and tweaked around with his 3.8 V6 Mustang for 11 years. I know... lol