Could not tell you if the crossover is open or not, but I do wait until the car is at full operating temp before getting on it. Have run quite a number of tanks through it at this point, so everything is fresh. Have worked on other areas of the car (starting with the rear and working forward) up to this point so have about 1500 miles on it now. The car runs, but not nearly the way it should. Others posted about going back to the AVS, or an Edelbrock. I had the same bog with the AVS, so putting it back does not seem like the right way to go.