Your talking nonsense. Of course a crack will have an effect on boost, it will be constantly bleeding off pressure when the wastegate door is closed, plus once hot the hole will expand combined with pressure being pushed through it. It probably seems like it boosts fine but the turbo will be working harder to hold pressure.
Sorry OP for chucking a spanner in the works, but best to find these things now rather than having to offer a refund later IMO.