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So all of them codes are linking to the ECU or the Lamber not getting the readings its expecting.

I had a similar issue on one of my R32's TWICE 

First time is was the brake servo hose near the back end of the engine that had a split, the second time it was a faulty MAF sensor.

Thing is with VWs you can have something as small as a split in a hose which then causes multiple sensors to go out of wack.
Clear the codes off, it might be "pre PCV" and didnt have the codes cleared down.

If the codes come back that I would get looking into the entire system, start with the cheapest things first.
Check your Diverter Valve part number, if it doesn't end in "D" then you will have the Diapham model which is prone to splitting, the "D" version is the Piston version.

But here is a break down of the codes which should help you check things.

P0172 – System Too Rich (Bank 1)
The ECU detects the air–fuel mixture is richer than expected.
Common causes:
- Faulty or dirty MAF sensor
- Leaking fuel injectors (on Mk6 GTI this is very common)
- High fuel pressure (faulty fuel pressure regulator or HPFP issues)
- Evaporative emissions purge valve stuck open
- PCV (positive crankcase ventilation) valve failure
- O2 sensor issues (usually front sensor)

P0441 – EVAP Incorrect Purge Flow
The EVAP system isn’t controlling vapor purge correctly.
Common causes:
- Faulty N80 purge valve (very common VW issue)
- EVAP leaks or stuck purge solenoid
- Blocked EVAP lines or charcoal canister fault
- Wiring fault to purge valve

P0303 – Cylinder 3 Misfire Detected
Misfire specifically on cylinder 3.
Common causes:
- Bad coil pack on cylinder 3
- Faulty spark plug
- Failing fuel injector (very common on Mk6 GTI)
- Low compression (carbon buildup on valves, worn rings, etc.)
- Vacuum/PCV leak affecting a single cylinder

If I had to take a guess, because you have already replaced the PCV, Sparks and Coils, its most likely going to be a faulty purge valve (N80) This is the single most common cause that can realistically trigger all three of your codes at the same time.

- It directly sets P0441 when it sticks open.
- When stuck open, it feeds unmetered fuel vapors at idle → rich condition → P0172
- That sudden enrichment commonly causes misfires, especially on one cylinder that happens to be most affected → P0303

On Mk6 GTIs the N80 is a very high failure-rate part. Cheap, easy to test, and easy to replace.
Simple way to test and replace the N80 purge valve, On the right side of the engine bay, attached to a hose coming from the charcoal canister. Looks like a small black plastic solenoid with an electrical plug. If you follow the hose coming off the intake tube (near the airbox), you’ll see it.

Remove the N80 valve from the hoses (very easy just hose clamps). Try blowing into one end of the valve with the valve unplugged (no power), it should NOT let air through.

If you can blow air through it with no power → it’s stuck open → BAD valve. Buy a new one and replace it, the part number should be written onit somewhere. Should be under £50, just order it via your local VW or TPS (Don't use a 3rd party or used part)

You can also do a shake test, Not definitive alone, but helpful. Shake the valve about whiles its in your hand.
- Normal: It should click/ratttle lightly
- Bad: No sound, or sticky feel

All great {plus some amusing} answers. Getting it done by a VW dealer so at least if there's any issues, its on them.
Much thanks again.

Crazy talk.

White, Red, Black, 'Signature Pure Grey' and More White.

https://www.vwpress.co.uk/assets/documents/original/26461-GolfMkVII.pdf

Blimey, is it really that bad?

I had Dynaudio in a mk6 and wasn’t that impressed. Then had it in a 7.5 and absolutely loved it.
Moved to an F40 M135iX with HK which had literally tons of speakers and I wasn’t particularly impressed at all.
Since then I’ve had 3x mk8’s with standard audio and don’t hate it. Would’ve had it in the middle car but it wasn’t available to order at that time for some reason and the other two were pre-built cars.

Have the standard in the 128Ti and its hands down the worst system ever listened to, my father red transistor radio we took to football in late 80's was better and actually not stretching that!

Wife has Dynaudio in her R and as much as always stated the standard stereo in my own R and TCR were decent, the Dynaudio lives up to its billing and does Heaven 17 Penthouse and Pavement real justice.

Did not have enough £ in bin for the Sennheiser upgrade on the incoming Cupra, but it really cannot be worse than the outgoing 128Ti system.

There must be a technical way of measuring the performance of the HK aside from ears?

Things to try...

1) Different audio source (bluetooth vs streaming vs something on a USB stick). I actually found streamed music sounded better?

2) Different types of track - yes some things sound terrible, but they probably did sound terrible anyway. Some of my 80's stuff has horrific production.

3) Do you have the surround sound activated? It can make some tracks you know well sound bad. I mainly have it turned off for anything retro.

4) The different mode buttons work in conjunction with the EQ. Try the different mode buttons....

5) The centre speaker even with HK is the same one made by Amstrad in about  1983. Swapping it out I think would make a lot of difference (there's a guy on here who sells the upgrade kit). I reckon you can hear that tinny speaker above everything else. It was the same experience I had with a BMW 128Ti that had HK - all i could hear was that centre speaker.