The stock NSR carb is very good. What makes the F3 ones even better is they are so basic. You don't need to run any of the air plumbing or the TPS etc (though you do if you want to run a normal PGM-III).

The F3 carb was designed to work without any of these as the F3 kit PGM doesn't use them.
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If I have to take the carbs off once more...