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Posting this here for anyone who is looking to do this upgrade - it's an excellent, cost effective option. Video is on a TT Mk2 but it applies for anything else in the PQ35 (8P, Golf mk5, mk6, Passat and Jetta) family.

All parts can easily be locally sourced, so it won't break the bank, and also using some OEM Audi parts. Rotors are a custom setup.

This will be a direct upgrade for 8P owners with steel knuckles/spindles/uprights (and whatever else you want to call them) - the main thing you want here is a thin brake caliper mount. The TT's upright's brake caliper mount are 15mm thick. So you can upgrade to those if you wanna keep allow hubs. Anything thicker and you will need to change them (i.e. the Passat alloy hubs are 33mm thick).

All the same ideas apply for the 18z's but you just need a bigger rotor and make sure to order the correct pads.

Audi TT Mk2 Epic Big Brake Upgrade part 2 - 17z Brembo Caliper & Forza 2 piece floating rotor how to

List of brake pad options for both 17z and 18z (working document)