No expert but,
Su's work on constant velocity. when u plant your foot down, u open the butterflies, but u do not raise the pistons inside the carbs. These pistons wait until there is more air entering the engine before they go up. In my opinion, it would be extremely hard to have su's which where to big.

with normal carbs, when u plant your foot, u increase the air passage way, and for a while, the air velocity enetering the engine slows down, this does not happen with su's.