I'm fairly certain I've seen on another thread someone tried and couldn't without serious modification on a similar center dump shorty header, because of fender+gearbox and k member clearance issues.
Y'know what, that makes sense, if the factory could have used a rams head design, they probably would have, but now that I think about it, the center dump would probably hit the steering gear, and the exhaust would be a pain because of the location of the K.
Hypothetically though, if it could be used, does anyone have a general idea of HP differences between a long tube header, and a stock manifold, compared to something like this? I'm just kind of curious now.