Thank you for taking the time to reply and for the information. I got a laugh out of the snake oil reference. Not sure if I can return the booster plug or not. Might be easier to list it on ebay. I guess the lack of posts on this forum regarding the boosterplug speaks volumes. I read some...
The surging on my RC390 seemed to be getting worse so I decided to try a booster plug. It arrived with instructions that were vague (as far as I am concerned, I am very familiar with jet skis but don't have a lot of experience working on motorcycles).
#1 on the install instruction sheet says...