I run them both. 1" 4 hole tapered Wilson in to a 1" open. They sit on a Victor 340. I know a 4 hole will improve the signal to the carb - could be better for street driveability. This is just my opinion, but the larger you can make the plenum and the farther you get the carb from the port runners ( within reason on a single plane manifold ) the more even the fuel distribution will be.