Look up the HP & torque numbers for that engine. I'd be surprised if the HP isn't greater than that of the I6, but I doubt that the torque is greater.
I always break it down like this: HP is the rate (speed) that the engine can do work. Torque is the amount of work that the engine can do. Compare an Indy car engine to an 18 wheeler's engine and look at what each excels at doing. Modern car and light truck engines seem to be more and more biased towards high HP at the cost of torque. Which makes sense if you only want to beat the shmuck next to you to the next stoplight, and that is all that John Q seems to care about anymore.
A friend of mine owned the T-100 that was the Magnusson prototype for the TRD supercharger kit. Fuel mileage was never great after the install. Everything that I've read since continues to support that. The truck did (does) leap small buildings in a single bound, but it had to get a second, 40-ish gallon fuel tank for extended Baja trips.