I agree with Greg, sounds like they tested the regular Edelbrock Performer which is only good for completely stock engines. Going to the Edelbrock Performer RPM or Air Gap on a 347ci would should have shown a huge performance increase so sounds about right. The RPM and Air Gap seem to flow about the same from most stuff I have read. Man look at that Torque, can't see the range but looks like a fun car to drive.
1967 Mustang Convertible, 289-4v, C4, Edelbrock Performer Intake, Mild Cam.