One of the reasons most modern cars lose power at high RPM is that most manufacturers have the ecu set up to slowly partially close the throttle plate as you get within like 1500rpm of the rev limiter.
I am not sure if Ford has the stock ECU set up to do this, but if so, a tune fixes it. I have yet to see an aftermarket tuner not eliminate that feature. I would bet it does it in stock form though. Its pretty common.
Also, breathing becomes an issue, so even if you have the throttle plate stay all the way open till you hit the rev limiter (which most aftermarket tuners set to 6800 from what I have seen) you still taper down a bit, so you want to do whatever you can to ensure air gets into and out of the motor as fast and as easily. HIGH rpm is where something like the FRPP intake manifold comes into play. On lesser modded cars it may not make much in the way of peak gains, but its runners are several inches shorter than the stock manifold (something like 5 inches shorter) and it has more plenum volume, both of which help shift power a little higher up in the RPM band. LT headers are obviously also recommended for higher rpm power, as are cams. Even a mild cam optimized for lower range power will still help out up top.
I know my car pulls all the way out to redline with no real tapering of power till it hits the limiter at 6800.
JLT CAI (V2)
GT500tb
FRPP intake manifold
FRPP hot rod cams
JBA lt headers
(A few other mods but those are the breathing mods)
I definitely have the strongest power from about 4500-5700 or so, but it still pulls hard all the way out.
