I suppose first you would have to define " power killer". Attaching a number or range of horsepower or even a measured difference in lap times that would have been considered a power killer at the time this carb was tested in cup racing. Without the details of the results of the testing that was done at that time it would be hard to determine. I'm surprised that if a super atomizing carburetor lead to "super vaporizing" the mixture in a way that displaced area in the intake tract and killing power as a result that Vizard wouldn't have been aware of this possibility. He writes in one of his books in detail about how in an air restricted class of racing that he removed the light ends of the fuel they were using by blowing air into a drum of fuel. The purpose was to prevent the vapors from taking up space that could otherwise be occupied by air. He claimed this was successful and gave them a power advantage. So it would seem that, true or not, Vizard believed at one time it is possible to kill power with too much vapor in the intake tract in a air restricted engine. Speaking for myself I don't know but find it interesting to think about.