Right now I'm running at the second from top notch and I usually like it that way with the NT's so I may get a bigger jet -LS
The close to the top you set your needle, the LEANER the mix, hence more air less fuel. More air runs hotter.
The lower the clip is set, the higher the needle sits out of the jet, hence richer mix, more fuel.
In other words, moving the clip is akin to a bigger jet with the needle in the same position.
Put you pipe on, set your clip to the lowest point, get it up to wide open full speed and with the throttle still wide open hold the kiil button until the motor dies.
Pull you plug and look at it.
If the white insulator inside is a nice tan color you are good.
If it is all white you are still running too lean so a larger jet may be needed.
If it is black or oily you are too rich, move the clip up a notch at check again.
One other note is get an Iridium plug and high flow air cleaner.
You can actually feel the performance difference.