Split hoses are defiantly gonna be happening all over the shop, Blocked PCV valves, cracks in turbo housing, (cant check unless u remove from car = massive job) oil in inrtercoolers (their 2, one on each side joined by 1 pipe across front of car. if lots of oil here - turbo rebuild time) cracks in head from overheat due to bottleneck in crap standard manifold and people not letting the turbo cool correctly, Maf sensors, Coilpacks (have they been recalled)
N75 valve, Diverter valve - may have been changed but what to, diverter valve needs to be forge recirc type if changed..
Water pump, these fail for fun on all newer Audi VW Seat Skoda due to plastic impeller, Cambelt goes if the water pump breaks
loads more niggle bits, these engines are awesome when they have had all this sorted
then, has it been mapped ? if so what torque ? rods bend, - id teir knocking on the engine, if this happens engine is fooked and will need full rebuild
Nick at carbon tuning said mine is the most loved and best condition 20VT he has ever seen and worked on... mine was a 42k engine and iv rebuilt it, i had many split hoses that will have hindered the performance for the first owner of the engine and also me when i first installed
My maf sensor was fooked, my coilpacks were, iv cahanged my turbo, and even my old K04 had a tiny crack in the turbo housing- its ok but this is on a well looked after turbo
TBH all this applies to all 20VT cars.
take vagcom with you if you have it, drive the car, should hold bost well and turbo should not make a flutter sound
6 speed gearbox is also a known weak point, and a expensive fix so make sure its tight and no noises
Also look for leaks on the rocker cover gasket and the tensioner seal (half mood seal) these 95% of the engine we get need changing, not a massive job but can make a mess if not sorted