I have the Flow 40 on my V6 when I put it on I left the reso on and it did not sound a whole lot different - then I cut off the reso and went with a straight pipe + tip - had that for about a week then the drone drove me nuts so I got an aftermarket reso -- sounds good now -- does have a bit of drone but I have gotten used to it -- sounds like the BB's glasspacks really get ride of drone all together so you might want to look into 1 of those!
2008 Charger Daytona R/T shaker hood,corsa,93 tune + low kms lol #053/100
2006 Charger SRT8 silver k&n CAI, suitcase delete, tinted tails
2010 Ford Flex Limited Ecoboost
1984 Chevrolet Caprice