The guy local paid 100$ (at some backwood place, and has a template for a true H pipe setup that can just be taken to be made) and the avg. price of f150 headers is like mid 300$ range (I know I looked into it and have a set of extra 94-95 stock headers to swap on someday this very way). I would guess that with a cat and a few exh. parts you could fab one up for cheap. I would talk to some exh. shops and see what they say, talk is free. They might be able to get you by with a chop at the manifolds and put the headers on and make something fit to where the chop was. They do make ball type flange starter pipes that could be used for this.