The early NC1 engines also have some weak points. It’s not a horrible option to get one of the 2.0s Joe has and boost it. The 2.0 is smoother and revs better. In order to install the 2.5, the balance shafts have to be removed.
I have 2010 soft top with a turbo, 230ish HP is a pretty good spot. Above that it is stretching the design limits. The trans on the NC1 has some weaknesses as well. It’s a good combo, as the GTI is a bit ponderous for the tight stuff.