I just like the sound of Flowmasters, that's why I use them. I fitted electric cutouts just after the collectors and my ET/mph is the same with them open or closed so they are not restrictive at my HP level. I use 3" delta 40's and 3" pipe all the way to the bumper.
Here's a nice clip of a Charger with Flowmasters.
http://www.youtube.com/watch?v=Hu8_uxk4hiM

1970 Road Runner 505 cid MCH CNC ported Stealth heads MP 528 camshaft 4 speed GV overdrive 11.98 @ 117 on street treads