Performer RPM modification

The only time the RPM intake would be worthless after having been cut, would be if installed on a set of factory iron heads. All aftermarket aluminum heads have no exhaust crossover passages.

Before buying the 440 Source dual plane pan, check with 440 Source to see if their valley pan will even fit the RPM intake, because, some dual plane intakes (the 6-pack in particular) do not fit the 440 Source valley pan.