Nexxussian - one issue to consider with SU's is the lack of accelerator pumps.
SU's were used primarily on engines with very little torque but high RPM. Performance in the lower RPM range's is marginal. Do a little research on the gear ratios utilized by the imports to allow the engine to obtain RPM quickly when torque was needed. Standard transmissions were also primarily used.
The lack of accelerator pumps does contribute to better fuel economy.
Some of the more expensive O.E. installations (i.e. Jaguar) incorporated an auxilliary electric "starting" carburetor to aid in starting, again because of the lack of accelerator pumps.
Jon
