I installed one or two Holley carbs when Harley came out with them back in 2001 or 2002 in their S/E accessory catalog and did get a 7 or 8 HP gain just bolting them on but they were a nightmare to tune. Even with a high dollar dyno and a few phone calls to Harley tech, no matter what adjustments I made there was always a bad spot, or maybe I should say a rough spot, could move the bad spot around with jetting and adjusting but it was always there, somewhere. That winter I was at the motor factory for a PHD course and talking with them I was not the only tech that had problems tuning them, they said they were taking them out of the catalog because they were just not a good road carb and had too many problems. The one thing that sticks in my head is I never want to see one again. Lol They might be alright for a race bike if you tune the morning of the race but not much of a carb for an everyday rider. If you want to keep the carb and put a good air cleaner on it you might have a local dealership search the dealer network to see if someone might still have a backing plate sitting around in their inventory for it. Other wise I'd recommend just picking up a good old CV carb.