The boost pipe connections are a common leak point too. Easily spotted by sweaty oil patches around the pipe connections and drips of oil on the undertray from the driver's side discharge pipe.
I'm in the process of removing them all of those pesky clip connections. 2 have gone already with a MK6 R intercooler and the remaining 2 or 3 are being deleted with a Spulen turbo discharge pipe kit. All that along with a GFB DV+ will give you a nice, fit and forget leak free boost circuit.
If not that, it's time to start doing some fault finding and logging with VCDS.