So......................an update
My plan, now I'm back in the UK permanently, was to sell the car this summer just gone (2022) to add to my house deposit so, before in preparation for getting it sold I wanted a few niggles sorted, mainly a smokey engine on start and at full throttle and an odd fuel issue which came and went at random, so I dropped of the car at MRC in April for some pre-sales TLC ..........................6 months later it's fixed and slightly faster than before
So what happened, well lets break it down -
Fuel - Occasionally at full throttle it would feel like car had hit a fuel cut (or starvation) but this only started after the new "in-tank" Low Pressure Fuel Pump was replaced with an uprated one so I wondered if I had a sticky injector dumping fuel (and pressure) causing the issue so I had MRC clean and test every injector with no issues found, so they checked further and managed to replicate the fault and it was the one of the engine bay High Pressure Fuel Pumps effectively collapsing (they word they used) under load so we fitted two new HPFP's which solved that. However during mapping the readings from the lambdas were "erratic" so we replaced all 4 lambda's.
Smokey engine - Juuuuuust a simple one way breather is probably failed, or so I thought. After replacing all 5 in the system (at my request) without solving it, MRC then suggested that the Oil separator could do with being replaced as well which didn't cure it sadly. Then they found that the right hand Intercooler was filling with lots of oil, causing the original smokey engine issue. They then traced the leak back to the RH Turbo which by now was 7 years old so understandable. Sadly that meant that the engine and gearbox were dropped and both turbos were sent back to TTE in Germany for a rebuild (they can rebuild old ones I found out, they just don't sell them so no need for £4k on new 1000hp ones) which seems to have solved that part of the smokey engine issue.
Smokey engine Pt2 - For the 1st 2-3 seconds after start the left bank burnt a tiny amount of oil, showing up as a blue puff of smoke. MRC found that some of the valve stems were leaking so we replaced all 40 of them, 4 per cylinder.
Rear Wiper - These are notorious for corroding and failing as the washer fluid runs through the centre of the spindle and mine had failed whilst at MRC so we replaced that.
Alarm Module - The physical siren unit has a battery inside and mine had corroded causing a fault to be detected in VCDS so we replaced the whole siren unit.
Servicing- As this was "pre-sale" I had a major service done, all fluids and filters (Engine, Gearbox and Diffs), 10 spark plugs, various other filters, seals, gaskets etc replaced.
Re-Map - As part of the rebuild MRC re-mapped the car again now they had a whole new fuel system and new turbos to play with and the car made 955hp (970ps) and 885lbs/ft (1200nm).
So whats next - To be blunt it's time to sell the car!
I've honestly really enjoyed my time with the RS6 but buying a house has now become my absolute priority and the car is just a huge chunk of a deposit sat there being unused for 5 days a week. Plus I now have space for two cars (one for Mon-Fri commuting and one for weekend fun) so I don't have to stick to owning just one car to do both (which the RS6 was great for) so the plan is sell up, buy a house and at some point afterwards consider getting something light and fun for the weekends (say <1000kg and 200-250hp) depending on how screwed I get buying a house with the current interest rate faff!