For the record, boost creep and a boost leak are completely different. Boost creep is when you, for various reasons, make more boost than you're supposed to. Typically, this happens with improper wastegate placement. You're unable to get enough exhaust gasses to the wastegate, so more exhaust gas gets to the turbine and it creates more boost. Think about the scenario this way: you have a 7psi wastegate spring in your waste. In a perfect world, on wastegate pressure you will make no more boost than 7psi. Anything in excess of 7psi goes right out the gate; it keeps the gasses away from the turbo and out the gate. The more flow, the more the gate opens to compensate (like 1 person pushing a car, then 2 people, then 3, etc).

Now, lets say your gate placement on your manifold is less than ideal. You'll push the 7psi spring enough to open it through the gate, but not enough gasses are directed towards the gate so you end up with more gasses going towards your turbo than your gate, creating "boost creep". This is when you'll make more boost than the wastegate spring is setup for (i.e. 10psi on a 7psi spring, wastegate pressure only).

A boost leak is where you have an (or several) opening for boost to escape before the turbo. For example, a vacuum line or a tear in a coupler for your intercooler pipes. This will not allow you to make enough boost because of the leak. Its like having a hole in your pocket and some change falls through it. You can put all the change you want in your pocket, but some (of not all) will fall through the hole.

Hope I painted a good picture for you all