exhaust dummy..

[I Eat Catfish]

I just got a 06 F250 at the end of Feb. I just got a 58v FICM from Swamp's cause the original took a big fat dump on me! I'm planning on getting a Gryphon and want to know about exhaust opinions. I've heard some people say "straight 4" no cat, no muffler" and others say "that engine needs some backpressure or it will be a slug to drive." So what's the deal? I'm not looking for a wild, smoke pouring tune, just a little more "oomf" and some better mileage.