I was just kicking on CL and saw a streetmaster for a song. Is it a good manifold for a 1983 E350 23 foot long. Engine is stock except dougs headers and 50 series Flowmaster. I am trying to pick up a little mpg with out loosing power. I installed the headers and picked up 1 mpg or better. Best before headers was 7.4 with nothing in tow. After headers and pulling a Ford Explorer I got 8.4. I usually tow with it but mostly my 4 wheelers. I just figured for 75 dollars if it would help I would go for it.