Yes the CA20 throttle flows more air, and (reportedly) bolts onto the A14 manifold with only a "little modification" needed

You can also fit a single butterfly throttle -- which will flow even more air. The twin-butterfly design I would guess is used to enhance the vacuum signal in the smaller channel. Frank used a 55mm throttle from a CA18


compare to the stock A14E twin-throttle body

Geoff thought 55mm gave poor throttle response (all or nothing)

Neal used a GA16 throttle body

Michael used Camira throttle body