I did the full top end on my Mustang including full exhaust. With a custom tune completed on the dyno after all these mods were done and after driving it around for a while on the stock computer, I netted 10 rwhp and 17 rwtorque. I know I'm not comparing apples to apples here, and I'm not trying to be a smartass, but I always take what I read on the net with a grain of salt.
Not to be a smartass, but if that's the best you could do with an intake, full exhaust and a custom dyno tune then you also need to replace the person tuning the car.
Tuning the 5.4 3v V8 is more than just strapping it on a dyno, advancing the timing and getting the A/F right -- especially with the F150. There are huge untapped potential with its tuning due to the things Ford does to make mileage numbers for the EPA.