Dumped a bottle of this in my fuel tank:
View attachment 45093
I'm not a lover of additives but I've had a problem with my Mrs's Merc. It needed a new (reconditioned) turbo actuator to solve a misfire on kick down. The problem was solved for several months but came back recently despite the actuator appearing to work correctly. The supplier suggested the variable turbo may be a bit sticky at the extremities of movement and suggested two bottles of Forte Turbo Cleaner. I was a bit concerned a load of crap would be dumped in the Cat but the car is smoother, more economical, much much more responsive and fixed.
OK my A2 does not have a variable turbo but the treatment claims to be good for cleaning the AGR valve and I suppose therefore also the manifold downstream of the AGR and the tops of inlet valves too. No harm in cleaning the turbo vanes either.
Will report later.