Nightrider FL - ViED Fuel Enrichment for EFI Harley-Davidson Plug - n - Play DK-FLVIED-10-NR The Plug-n-Play FL-ViED-10 richens the Air Fuel Ratio from14.6:1 to a range of 14.3-13.9:1 in closed loop mode. This Variable Fuel management upgrade allows you to fine-tune the air fuel mixture with a small screwdriver. Immediate Benefits: Lower Engine Temperature - Lower Exhaust Temperature - Improved Throttle Response - Reduced Surging - Reduced Pinging Recommended for: Stock Configuration - High flow air cleaner - High flow exhaust - "Stage 1" (both high flow exhaust & air cleaner)