Save your money. That thing has a very limited ability to help on the closed loop BMW boxer systems. It doesnít so anything at all when the bike is running in closed loop (that is during most light throttle, steady throttle, & in the dreaded surging operating range).
If it helps at all it would be on throttle position changes like light acceleration & the BMW is already pretty good in that particular area.
It will richen the system on starting & cold engine operation & in my estimation cause over fueling on a cold start & cold engine rideaway. That can cause more engine wear as overfuleing cold can wash the cylinder walls.
Before spending big money on things like this expensive resistor just try unplugging your 02 sensor then riding the bike for a while. That will richen the fueling a bit in the areas that matter (like the surging range & light throttle study cruise).
If you have money to spare then you would be MUCH better off getting an adjustable Techlusion fuel controller than that expensive Booster Plug intake air spoofer as the Techlusion allows the fueling to be modified in the ranges that matter like the surging operational range & light throttle cruising.
Also be careful on what you read online on things like the booster plug & similar devices as they can help on certain motorcycles. Mainly on open loop motorcycles like the early Ducatiís. Some motorcycles (mainly open loop only fuel injection) does use the Air Intake Sensor more for fueling control. The BMW boxer is a closed loop system so doesnít rely on the Air Intake Sensor for warm engine light throttle fueling control.
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