Overview Reviews Product Description 300-137 Holley EFI Holley Single Plane EFI Intake - GM LS1/LS2/LS6 Single Plane EFI LS Intake Manifold. All GM LS Gen III or IV engines equipped with LS1/LS2/LS6 style cathedral port cylinder heads. Product Videos Custom Field Product Reviews Write a Review Write a Review × 300-137 Holley EFI Holley Single Plane EFI Intake - GM LS1/LS2/LS6 Rating * Select Rating 1 star (worst) 2 stars 3 stars (average) 4 stars 5 stars (best) Name Email * Review Subject * Comments *