| RE: Aftermarket exhaust manifold for 4.7|
Do you mean headers?
If your're manifolds are OK, I"d leave them alone if I was you. UNless you have lots to spend for little gains.
On the 4.7, biggest bang for the buck is cams, even the DC HO cams. Then a true dual exhaust with a new Y pipe/ or a proven tuner, like SuperChips, not others like Jet, etc.
Loose the cluch fan, ~3-5hp, free.