You need to have a word with your mechanic because that's not a carb boot!
What is commonly referred to as the 'boot' is in fact the intake stub which connects the carbs to the cylinder head.
What he's shown you in the photo is the connector between the airbox and the carb. An air leak there won't cause any problems at all with the fuelling.
You maybe need to make sure he understands what he's supposed to be doing if he's supposed to be modding the intake stubs for a Full Monty Ivan's installation.
Also, there's no need to remove those airbox connectors if the carbs are removed properly.
Why do I have an uneasy feeling about this ...