I can vouch for Dave at PDT tunings maps, just sold on my Mk4 Golf TDI 130 which he mapped at 189, transformed the car, same economy and no issues over 35,000 miles, I wouldn't let the mileage put you off. My golf before was on 350,000 you just need to service them regularly and obviously, not drive the pants of it constantly, mechanical sympathy extends the life of a car.