Edelbrock 75254 Performer RPM Air-Gap Dual Quad Intake Manifold Comes with EnduraShine finish which resists discoloration from heat Basic operating RPM ranges from 1,500 - 6,500 Measures 4.57" tall in the front and 4.92" tall in the rear with port dimensions of 1.92" tall x 1.16" wide Center to center distance is 6 7/16" Includes a three step vacuum metalizing process to enhance abrasion and chemical resistance