Haven't run any ET tests, but the 4781 on my Duster sits like the OP's photo, has a milled choke horn, and I've had no problems. Milling the choke horn off improves CFM and feeds air into the carb more efficiently than having it shrouded by the choke tower. I wouldn't expect much ET out of it, but I'd bet the MPH would pick up a little from the improvement in mixture distribution.