They are known to crack on the fittings so that could explain the tape.
Shouldn't make a difference on boost unless your check valve is buggered in which case it could be letting boost past.
Could effect your vacuum on idle and brake feel though, the brake assist wouldn't be as strong so you'd have to push the pedal harder.
part number is 1K0 612 041 GM for the whole lot and plus you need 056 129 777 which is a little cap to cover the unused nipple on the newest revision of the brake booster kit.
^^ I only know that because i've jut had to order it for mine.