[Black 65 GTO]

I have run a couple different intakes on my '65 389, factory '65 cast Iron, Performer RPM, and Edelbrock P4B. The current intake in use includes the Edelbrock P4B. I have noticed a substantial improvement in low end and mid range with this old P4B manifold over a Performer RPM, not to say that it's the "perfect" intake manifold but it works well for my application. If you are running a 389/400 using cast iron heads, with an shift RPM of no more than 5500,I would not hesitate to use this manifold, if you already have one as I did. I feel that even a mild street/strip 389/400 w/ stock D ports might be better off with a smaller intake since the Performer RPM has a large plenum and bigger runners compared to a Performer/P4B. If your buying a new intake, I would purchase the Performer. I would imagine that you would find comparable performance on the street between the Edelbrock Performer and the Edelbrock P4B.