Videos don't do this system justice. There is no resonance, but you're going to hear all sounds coming from the exhaust echo off the ground right behind you which at certain RPM's will cause bass/vibration.
I find that any increase in throttle whether it be accelerating up to speed or simply maintaining speed on a hill is a lot louder. Idle and cruise at constant speed/rpm on non-hilly areas isn't bad at all and actually just a bit louder than stock.
My opinion is that the WOT of this system is well worth the reasonable price of admission. Worst case scenario, the connections are all slip fit and held in place by band clamps so it wouldn't be a big deal to start out with this kit and add a more traditional exit later to kill the echo off the ground.
I'm sure the sound of this system has people wondering what if MBRP made a lightning style exit. Also, I wonder why MBRP has some T304 systems for other vehicles, but not the Raptor. Seems like people would pay the additional cost if it was available.