I've had a search and found Big Num had a similar problem to this 5 years ago but the thread contained no result.
The car has had new plugs, NGK - BCPR7ES - gap 0.7mm, coil-pack connectors overhauled etc. and now it has a hesitation at low revs except with very light throttle. Once the boost is up, and particularly on the second turbo it's revving cleanly as it should.
The symptoms are hesitancy and the odd pop from the exhaust. Is this a low-revs fueling issue and if so what could be causing it? I don't have any afr measuring kit.
There are no stored error codes.