Multiple slots in the needles in a US-spec Bandit is a sure sign of a jet kit! The US-spec stock needles are not adjustable. EU/UK and some other markets do come with adjustable needles though. I've never heard of any kit requiring to go to the lean end of center, and certainly not to the top.
With a 1G B12, you'll probably want to do the 2" hole mod to the lid before you richen the needles to 3rd up from the bottom though.