I don't think duals are worth the money at all at least not on our engines... I have a Flowmaster 40 series w/ 2.5" piping from the cat back, and love the sound of it... I have heard a few folks that have the Magnaflow mufflers and they sound pretty nice, just not a whole lot louder than stock... Then again I'm sure if you replace the cat w/ a highflow unit... the exhaust would probably be nicer sounding and would def free up the flow of exhaust...