Hello,
sure there are higher rated Diesel specific turbos available. A direct fitment to the 90 PS TDI engine for instance is the KP39 turbo by KKK respectively BorgWarner Turbo Systems (BWTS) featuring a 46 mm compressor plus 38.5 mm turbine.
You may need higher rated injection nozzles and preferably a larger exhaust unit that allows proper “breathing“. A bigger intercooler would be recommended as well. Of course a custom programmed motor chip is mandatory.
A problem still would be the too weak gearbox for up to approx. 145 HP + >320 NM of torque and a lack of space to fit a recommended bigger intercooler. A turbo lag considerably wider than “stock“ can be expected.
However, pistons + pin, crankshaft and conrod should cope up well with that much of power - see the „big brother“ 1.9 TDI.
Fuel consumption should rise considerably though as well as most exhaust emissions. Latter may lead to MOT probs...
