 The black plastic air inlet tube was replaced with a larger diameter fancy looking carbon fiber inlet tube to match the larger throttle bore in the plenum.The air cleaner box base was modified to increase the airflow.The Lucas GEMS ECU was calibrated to support the mechanical changes to the Callaway engine (the Callaway engine had the same basic FI as in 1998 and did not have the Bosch system that was on other 1999 HSEs).