I'm currently running a 670cfm Street Avenger on my mustang. I am very happy with it. It comes with three different springs to tune your secondaries with and it takes about a minute to change them. One difference between the Avenger carb and the old 600 vac secondary I had before is the Avenger uses a dual feed system like a double pumper so I had to buy the chrome fuel line kit. It also feeds on the passenger side, my old 600 connected to the fuel line on the driver side. I have a picture of it installed in my photo album you can check out if you want, it's a good lookin' carb in my opinion and definately has great punch.