Well I have Magnaflow installed on my 1990, Jim W has magnaflow on his Aurora ( V-8 and yes it does sound old school on that car, it'* purely awesome when driving), and smellbird has magnaflow on his car.
I like it cause it does have a nice deep sound.
Here is smellbirds car after he dropped us off when I blew my engine.
Right click and save target as
Here is my car on it'* first run after the new engine was installed.
again right click and save target as.
Now anyone who has herd smellbirds or my car for that matter, will agree that video does not do it justice.
All I know is that people who have gone Magnaflow instead of Flowmaster are glad they made that choice. The Magnaflow muffler used on mine anyhow was the single in, dual out made for the Camero.