The drone is an annoying hum in the cabin of the car -- usually cruising over 60-80 kms -- I had a flowmaster 40 on mine and and aftermarket resonator sounded great on startup and cruising around town but I got sick of the drone on my long drives - so I picked up a dual r/t system but now I am looking to get some more grumble out of it
I don't know what is best for the 2.7 but I am sure some more people with better knowledge will post stuff for you!
From what I have read over and over I think your best bet would be a Blastin Bobs kit.
bottom line is get a dual system because you will end up wanting one in the long run!
2008 Charger Daytona R/T shaker hood,corsa,91 tune + low kms lol #53/100
2006 Charger SRT8 silver k&n CAI, suitcase delete, tinted tails
2010 Ford Flex Limited Ecoboost
1984 Chevrolet Caprice