Explorer doesn't come with an E cam. E cam is 220/220 .498/.498 and has a good idle lope. The explorer cam was waay less aggressive, down under 440 lift. It does favor the exhaust side, however. I could probly measure if I really needed to, I have an explorer cam, Cobra cam, GT cam, and an E cam laying here.......

An explorer motor with an E cam would be a 300 HP motor easily.

Call one of the three C's (comp/crane/crower) to see what they recommend for low-end with GT-40P's.

The 5.0 does have a bit higher powerband typically. The six grunts a bit better than a 5.0 in a truck typically, now you see why. Almost as much torque and at a lower RPM.

On the headers, call FRPP, their shortys may fit. All FRPP Mustang Shorty's fit P heads now, but they have a slightly different hookup than a truck to the Y pipe. Hedman LT's will fit with a bit of massaging.

I would recommend changing valvesprings, stock Explorer springs were weaker than even a GT 'Stang.