Magnaflow gets my vote, deeper sound, Flowmasters are a more raspy sound, that said i run Magnaflows on the rat. My DD originally had dual Glass packs and the system ran side by side, the packs burned out but the forward pipes were still solid so i left them and had a 2 in 2 out 70 series Flowmaster installed, but also has 2 20" resonators installed so its deeper and not as raspy sounding.
Start combing Youtube and the MFG sites for sound clips.
I forget what mufflers i have but they are the largest body Magnaflows that were available, i wanted quiet after 20 years of headers and flowmaster 40's.
https://www.youtube.com/watch?v=ZyYm...ature=youtu.be
https://www.youtube.com/watch?v=wH4Qq3m7PPo