it will sound alot different w/ true duals...alot better for that matter if you go w/ the right setup. i also have a 97 4.6l and i cut my mufflers off about 2 months ago which as you know is a HUGE improvement over not even being able to hear the car as it was stock. but for me, that was only temporary. i just did true duals earlier this week actually. i had the third cat cut off, and had a single dual in/dual out flowmaster welded in its place and ran 2.5'' pipe all the way back on both sides, ending w/ trans am tips. im a big flowmaster fan, cuz thats what i have on my other bird too, however magnaflows sound very good too (my bro has magnaflow on his 5.0 explorer). my setup now is no louder that it was w/ just cutting off the stock mufflers, but it just has a MUCH better sound. its alot throat-ier and just sounds meaner...just a cleaner sound. in my opinion, its definitely worth the money and its a huge improvement. as for where to get it done, cant really help you there...im in VA haha.