which upgrades would you suggest for a d2 prefacelift

[notorious]

I routed them via A-pillar which you have to remove anyway to cut existing windscreen.This is not standard place for those wires.

The standard route is via B-billar and then behind headliner. There is special plastic thing where b-pillar meets headliner specifically designed for wires not to stand on the way of curtain airbag when it deploys. You will need to lower headliner a bit if you go this path and whole b-pillar trim should be out, which is rear seats out job. I think you'll need to do it anyway as you're routing wires to boot.

If you decide to go via a-pillar you'll have to route wires near airbag. Make sure you route wires in such a way that when airbag deploys it will not throw wire into passenger.

Make sure you purchase upper clips for a-pillar trim, which are designed to control airbag deployment. You'll most probably damage them when you remove a-pillar trim.

Did you ever remove a-pillar trim? Removing a-pillar trim deserves a separate article. It is very easy to damage a-pillar trim because of that idiotic airbag clip. A-pillar trim can 'crease' in the middle and that 'wrinkle' will always be right near your nose when you drive, always reminding about mistake.

If you find windscreen specialist who can cut windscreen without removing a-pillar trims and without damaging them / making them dirty I'd suggest going that path and route wires via b-pillar without completely removing a-pillar trim. Pay bonus premium to windscreen specialist. It'll be easier than finding good a-pillar trim without crease. They are only available from audi tradition shop not in all color combinations and cost about £150 each. Used ones are all damaged/creased as people don't know how to remove them properly.

Apologies if it sounds confusing.