No, just remove the 'Y' piece (lift it up and move to the side to release one of the 'arms' of the Y) then electrically connect it so it doesn't throw a DTC so you can do a manifold vacuum draw test one each side independently to see if there's a difference, but as you mentioned earlier that it cut out whilst driving with the previous owner, then it's probably not a relevant test as it'd still run on the other bank as mentioned earlier.