^^^^^ What he said. Maybe this will help.
The chambers in the Flowmasters give them that distinct "hollow" sound that FM fans love. Magnaflows don't really have that...in my experience the Magnaflow was deeper and had more bass to it.
Like I said above...the power difference wasn't night and day or anything but I did notice it. The truck would pull longer up a hill before having to downshift and just seemed to not have to work as hard to get around. I feel like I should add a disclaimer, lol. "Results may vary!!!" But I am a Magnaflow convert. The FM duals on my hemi sound pretty good but I think about what it will be like after I get the MF on it everyday.