Edelbrock Carburetor, Thunder Series 1812 AVS, 800 cfm

How do these perform?

Exactly the same as the AFB except the secondary air door is tuneable to avoid the bog the AFB gets due to the secondary velocity valve slamming open early without a pump shot to cover it.

With the tuneable air door you'll find more torque and a smoother transition into the secondary side if the spring is tight enough.