Another thought:
How come more guys dont dial in the tune as much as possible on the box with the filter off so inside the carb can be SEEN!! So now you can see the idle gap during the tuning process and dial in the LSN that way with the pinch test to get really close. Now you can know for sure youll have the LSN at a good tune and the idle gap set correctly then you can put filter on and drive the track tuning the HSN and dial the low end and idle in again a bit more