I would think that if you are worried about what oil best suits the tune level your car is at, then why not use what it seems others in your situation use which is a Miller brand oil.
Quantum will be good enough for factory spec cars, it is nothing special, just an oil rebranded as Quantum for sale mainly by VW Group dealerships and has been approved by VW Group for use in a range of engines.
Edit:- to be honest, if I had upgraded the engine in my car beyond factory spec, I'd be using a specialist for my servicing, very basic tasks on normal cars are all that gets done in dealerships - as far as servicing is concerned.