Has anybody experimented with or installed any type of exhaust/header modifications directed at increased performance of their Ford van with a 5.4L V8? Any installers on the West Coast. I've e-mailed several companies and no one seems to want to do so. Any other available aftermarket modifications that will increase torque/horsepower on these gasser engines?
On the 5.4L, your best bet is with a cat-back system. We did this on my brothers expedition, using a MagnaFlow setup. Nobody makes long-tube headers for the 5.4L, and shorty headers decrease low-end torque. The cat-back setup add some oomph all arounds. It was noisy at first but mellowed out after a few weeks.