These carbs were an option installed by Donald Healey in England shortly after I bought the car from him. They installed them along with what they called a "high efficiency exhaust system." It was headers and a pretty much straight muffler. Back here in the States Dave Tabor reworked the engine to what he said was as much as could be done to it and still have a street driver. It has the valves fron a 1098, the head was shaved 0.080 and it was bored 0.040. Along with that the engine was balanced and the flywheel lightened. There is also a hot street cam. It ran very well for me for nine years before I pulled it to do the body rebuild that I just completed.