Servicing is key. Any proof of major work too. Proof of gearbox oil changes and oil changes on the quattro system. Make sure all electronic items work such as AC as they can be expensive to fix. Also check out YouTube buyers guides
Under MOT rules MOT testers can only check the parts are fitted, not if they've been blanked out of the ECU. Garages are suggesting this as it's far cheaper than changing the egr.
Welcome to the forum you'll find the members on here are a friendly and helpful bunch 🙂 I'd recommend a diagnostic check to see if any fault codes flag up. Best taking it to darkside for this as they've done lots of work on it already.
Looks a good project. Could it be injector seals rather than the injectors?
I'd recommend doing a full service. Check the brake pads, sometimes the wires and sensor that warns of worn brakes can in fact break.