I apologize in advance if this is a stupid question or if you need more info in order to answer it.

If I have a relatively stock 440 engine....
(.030 over)
6-pack intake setup
Mopar purple cam (509 lift)

And I want to upgrade from my stock 906 heads to a set of the Edelbrock Performer Aluminum heads, approximately what kind of HP gain am i expected to see ?

I'm currently running stock (HP Exhaust manifolds) but willing to upgrade to headers if I have to. I prefer to stick with the stock manifolds.

Thanks for any help

Gary