i have a 670 street avenger holley carb. w/5k miles. imo the best one can do in a vac secondary carb. i need a 6-750 holley double pumper carb to modify for blow threw application (turbo) and i can't use this street avenger. (vac. secdary) this carb is perfect for 300 to 400 hp sbf . the street avenger features: easy vacume secondary adjustment, external adjustable float with see threw sight plug, duel feed , center hung floats, power valve blow out protection, ford a/t kickdown. i will take some pix when i get to my shop today. send upon request.