The plugs on the 1.4T can be run up to 0.037" However, due to plug gap growth you will very likely start experiencing spark blowout under higher loads starting around 2500 RPM. Because of this GM came back and changed the gap for new plugs to be 0.025" to 0.0274". Set new plugs to 0.028 and older plugs to 0.030". I just put my NGK BRK7EIX plugs back in and set them to 0.029".
Put them back in, as in, you took them out at some point?
I just put a set of those in mine a few weeks ago.