1st mod for the 1.8T should ALWAYS be a chip. Check out the sticky for GIAC, best bang for the buck mod out there. Then upgraded DV, Intake, Downpipe, and Exhaust. Those are the main bolt ons. It will be a good bit faster with all that stuff. After that you could go with a bigger turbo, but i would start with the basics and see if that satisfies you.

What do you want for the interior? Didnt the GLI already come with aluminum accents and Recaros?