AFN Engine: 160HP, 400Nm - Safe or Risky?

Hello,
I recently became the proud owner of a Seat Ibiza, model 6K, manufactured in 1998, with an AFN engine. The odometer reads 130,000 km, and there have been two previous owners. According to the documents, a chip tuning modification was performed at 102,000 km. That's the basic information about the 'hardware.'

Now, let's talk about my problems:
'My engine frequently goes into limp mode and only delivers power as if it had 64 horsepower. If I turn the engine off and on again, it usually works fine. The error code in the system indicates a 'charge air pressure control difference.' Strangely, regardless of the gear, it doesn't start accelerating properly until around 2000 rpm, sometimes even 2200 rpm. The average fuel consumption is around 6 liters (with 215/40/16 tires), but I've also managed to get it up to 7 liters with more aggressive driving.'
'For comparison, I have the car of my ex-girlfriend, also an Ibiza from the same year, with the same mileage, the same AFN engine, and the original tire size 195/55/15.'
'No matter how I drive this car, I've never exceeded 5 liters per 100 kilometers. With normal driving, it's usually around 4.3 liters. Also, the torque starts to translate into acceleration at around 1500 rpm.'

I just visited a smaller tuning shop in my area. They took me for a test drive and used a diagnostic tool (a VAG 1551 or something similar) to check my car.

His statements: LMM values are within the normal range, but the boost pressure is not building up correctly.
In numerical terms, it would operate with an initial pressure of 0.3 bar, and only at 2000 rpm would the pressure reach a maximum of approximately 0.8 bar, which is clearly too low.
This would also create a difference in the set parameters, which would lead to a fail-safe mode.
His guess: Turbo completely destroyed!
He mentioned that in my turbo, a variable geometry system adjusts the turbocharger pressure based on engine speed, and that this system can sometimes become clogged or, potentially, a blade could break and get stuck if the engine was improperly tuned.
The turbo sounds pretty awful. I had to give it full throttle a few times while idling, and compared to the turbo in my previous car, it sounds really strange. It seems to run for a much longer time with a terrible whistling sound.
It's also possible that the turbocharger is simply losing pressure somewhere (due to a leak), but based on the turbocharger noises, that seems less likely. (Supposedly)

He has a 3G variant, also an AFN model, which we test drove. It has a special KKK K04 turbocharger and a custom exhaust system (70mm diameter!!!) that was specifically tuned on a dynamometer. It produces 160 horsepower and 400 Nm of torque, but the power delivery is designed to be 'soft' at low RPMs and available throughout the entire rev range.

Test drive:
If I hadn't seen the tachometer and hadn't heard the engine, I would say it was a gasoline engine (with an upper RPM range of 4000 to 5000). The car starts accelerating so intensely from 1300 RPM, it's unbelievable, but there's absolutely no wheel spin, just excellent traction (with 195 tires and a sports suspension). And what's amazing is that the torque doesn't drop off; it pulls relentlessly in every gear, even in 5th gear, up to just under 5000 RPM, which is when it shifts. There's no noticeable drop in torque, even at 5000 RPM. The lack of wheel spin is likely due to the variable mapping, just like the fact that it still pulls at high RPMs (5000 RPM), or rather, it's due to the larger amount of air supplied by the turbocharger and the 1.5 bar of boost.
According to the odometer, the Golf has 255,000 km on it. It was allegedly chipped at 20,000 km and this large turbocharger was installed at 200,000 km. Due to this torque limitation, the clutch, driveshaft, transmission, etc., would not be subjected to extreme stress.
According to the MFA 1 display, the fuel consumption was 5.4 liters (which was high because we were accelerating very quickly), while according to MFA 2 and after driving 800 km, it was 5.0 liters.

Is it possible that my Ibiza could technically participate?
'The question I have now is whether my turbo is actually defective, or if it's just being told to me that it's broken so that I'll be more inclined to get the upgrade with the larger turbo.'

I also wanted to have a WAES (Waste Heat Energy System) installed, but that only makes sense if I have a larger loader, because the energy output is very low with a standard loader, as the flow rate is probably too low in the upper range.

I hope this wasn't too long and complicated to read .

Please share your experiences regarding my turbocharger issue.
'And I'd also like to hear your opinions on this large loader, especially in relation to its exhaust system or WAES, regarding its durability. The tuner made a professional impression; he explained a lot, warmed up the G3 properly, and didn't give it full throttle until the oil temperature reached 80°C. Even with aggressive full-throttle driving, the oil temperature didn't exceed 92°C!'
I didn't have to pay a single cent for the test drive with the diagnostic device .

On Tuesday, he will tell me approximately how much the so-called 'expansion phase 1' will cost.
'The exhaust system, along with the other modifications, would cost around 4000 euros. Without it, the cost would be significantly lower (and it would produce approximately 20-30 Nm of additional torque). An adapter flange allows the use of the stock exhaust system with the turbo. The KKK K04 turbocharger costs approximately 1300 euros, but it's only really worthwhile with a modified engine control unit.'
And everything would result in better emission values than before, and the WAES (if desired) can be registered with the TÜV (German technical inspection authority).

Answers and opinions, please don't be too complicated, as I'm new to TDI and have only just started learning about TDI technology.


Best regards, Maik.

*rub eyes*

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