I have not had a leak there, but if you did the symptoms would be a hard brake pedal and a funky idle, in other words your engine would surge and the ICV would try to compensate causing the RPM to go up and down at idle. If this is a 104, it should be a large plastic black hose that leads directly from the intake manifold to the booster. Good luck!
Regards,
Brian

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Brian W. Heitman

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