Headers can be aluminized afterwards,used to have a set of Hookers that where aluminum coated way back in time by some previous owner and they looked great,except for the usual smashed bottom of 3 tubes on the driver side.however i dont think i would like to have them bent from aluminized tubing due to how the tooling affect aluminized tubing while bending.
I used to work with exhaust manufacturing and among many things i did work with a mandrelbender and they can be pretty hard on the surface of the tubing and from my point of view a much bigger isue working with headertubes than on a catback or headerback system due to many big shortradius bends close to each other. regular exhaust parts is bigger in diameter,runs mostly on bigger diameter radiuses,bends are not stacked efter each other half as bad and bigger diameter tubing means much bigger affected surfaceareas supported by the wiperdie and clampingdies. Not to forget the abuse the headertubing sees being fited to the flanges.
Regarding the rust isues on such a new set of headers,that not accetable and should not happen,i would guess on bad prepwork.
