Street Demon vs AVS2

I have the 625 SD on my 75 F250. 351M, BW T-18 4 speed, Dana 60 with 3.73 gears. It's a big *** truck and will haul *** for what it is. I can make it get decent mileage if I just use my big toe on the gas pedal. It'll bump 20 as long as I keep it at 55 and no faster.....which is a tick over 2100 RPM. Any faster and the mileage suffers exponentially. It's pretty humorous, actually. In 5MPH, from 55 to 60, you can start to watch the gas needle move. But that's not the carburetor, that's just the physics of the truck and gears.

All that said, from what I've read about the AVS, you'd probably be splittin hairs to find a real performance difference between the two carburetors. Just pick one. You're not gonna miss out on anything.