on the 4.7, headers are not really needed as your stock manifolds flow the same if not better thant the headers that are out there now....
cams and intake will help you out on the top end, that is for sure. fact that is the cheapest mod out there (
www.socaldakota.com best prices around) exhaust, go with a X pipe and grab a F&B tB if ya can fit it into your budget.
better yet,
www.gsmotorsports.com for a exhaust for your truck. pricey but street proven and worth it.
the 4.7 has plenty of torque, not many mods out there for tq, most of the stuff out there factors on the high reving top end.
contact B&G Chrysler for a ECM flash, that would help a little as they can take out the Tq managment that is in the ECM.
as you can see, cant have both (TQ and HP)... there is a sacrafice in that area.