Very interested to hear the outcome of this, as if it works its a whole lot cheaper than having the injectors properly cleaned off the car.
It won't be as good as removing and cleaning them by striping them down but it can clean some up enough to be acceptable again
Not used it on the A3 as yet but have direct purged older diesels with good results
Best way for us to check is with VCDS under injection quantities or similar, it'll list how much work each injector is doing... Sorry can't recall the acceptable differences, a purge will show up before and after results!