I have 18's and ACC on my petrol gti and I hate it when the suspention is set to normal (it feels like a civic type R on sport good from time to time ) and have mine set to comfort all the time apart from going mental. Thing is we are not sure if the diesel suspension is exactly the same stiffnes as petrol suspension.
So drive ant deisel with 18's acc or not and go from there, if it's to hard get ACC.
Plus sunroofs are gay, noisy when closed even with the cover, worse when open, burns your bonse when your bald and messes up my golden locks if i was in full drag which I would if I had a sunroof.