Chip Chip Chip.... should be 1st mod.
I think here you have enough help, alot of vets vw/audi owners, Me being a newbie myself to the dub world.

I have chip alone in my TT.. 1.8t /ko4 turbo. Chip & DV.. I ran a 14 flat, which has been my best run..

You should do chip + DV and start from there.