As a general rule, if the
airflow to an engine can be increased, then fuel burning efficiency increases.
If no additional fuel is added at th same time then this increase in efficiency
results in more power at increased economy.
The Series III Stage 1 V8 engine has an airflow restrictor in the inlet manifold,
It consists of a disc shaped insertion with 4 10mm holes in it. If this is removed
then there is less restriction to airflow. To remove it, remove the carburettors.
If fuel economy is the motivation for carrying out this modification, then it
is a good idea to also check and adjust the carburettors, check the float levels
are correct and check the exhaust emissions.