Well John answered this one again , said 12 hole works been tried and tested end of discussion, couldn't get an answer on EHR except it could get plugged.
But why 12 holes?
Question why not 4 slots x 1" wide x 3" ? Not enough restriction?
OK after viewing the pic of the 12 hole mod I understand, I understand that CV carbs require a certain amount of neg vacuum and with the snorkel plugged the 12 hole mod creates this and increase air flow, that s why I was also asking on another thread about the slides if they required a mod also?