I have to agree that when tooling around town it makes the truck feel sluggish until you mash the go-pedal. Then it wakes up and accelerates very, very well for a truck of this size.
To me, adding an aftermarket exhaust exacerbates all of this because you can now hear all of the different 'modes' the engine is going through with 10 different gears and varying degrees of cylinder participation depending upon load response.
All in all, it is something I have to get accustomed to as this is the way of the future, the linear and confident pull of a V8 truck pulling on all cylinders all the time is something from the past.