Well its gonna have to run rich all the time. Carbys don't differentiate between pressure levels. All they see is a pressure drop across the venturi. That pressure drop might be 1psi natually aspirated, then add boost and the pressure drop is still going to be 1psi. I might not be explaining it best, someone else might be able to help. Carbys off turbo cars have a pressure compensator and add more fuel as the pressure rises. Ive always thought using twin charade turbo carbs on a corolla twincarb manifold (they should bolt up from my research) could be a good way to go. Theyre off a 1L motor so two of them should be good for a fair bit of power. They can take some boost, I knew a guy who was running 20psi through one on a charade :y: making 200hp!. Apparently theres a problem with them blowing the seal out around the throttle pump, there must be a fix for it though.