I have the opportunity to purchase an Edelbrock LD4B intake manifold alone or a stock cast iron intake (?year) with an Edelbrock Performer 600 cfm carburetor for the same price.

I want to put either one of these on my '71 Dart GT with a 318, auto (A904), 3.23:1 sure-grip 8 3/4" rear end. The car has electronic ignition, and dual exhaust (manifolds, 2 1/4" pipes, and FlowMaster 40s).

Everything I hear about the LD4B is that it is great for a 318 (port sizes match). But, will there be a significant performance difference (excluding the weight factor) between the LD4B and a stock cast iron manifold?

Basically, if I go with the cast iron manifolf I get the Edelbrock Performer 600 carburetor free. Is the LD4B worth giving up the free carburetor?

Opinions please!!