What the max hp using stock magnum heads

I believe the factory 5.9 magnum is 9.1 compression. The factory 380hp crate motor used a production line engine originally. 288/292 advertised duration 230/234 @.050 .501/.513 lift for the cam . Factory dyno tested at 380hp with a 650cfm carb with a 750 carb they were over 400hp. That was with upgraded springs, locks and retainers.

150 shot of nos probably 500hp or so.