Overview Reviews Product Description 534-211 Holley EFI Adapter Kit Required when directly connecting Holley fuel rails to GM factory fuel line quick-connect. Includes (1) 3/4-16 O-ring port plug and (1) -6 to GM quick connect adapter. Product Videos Custom Field Product Reviews Write a Review Write a Review × 534-211 Holley EFI Adapter Kit Rating * Select Rating 1 star (worst) 2 stars 3 stars (average) 4 stars 5 stars (best) Name Email * Review Subject * Comments *