DuTTCH

The model year 2000 have K03-035 Turbos
Borg Warner (Turbo manufacturer) rates maximum horsepower @ 195HP

The model year 2001 and up have K03-052/053/058 Turbos (also called K03Sport)
Borg Warner rates maximum horsepower @ 215HP.

The difference lies in the compressor wheel which is 5mm larger on the K03Sport and has a more efficient blade design (i.e. sharper angles which improves high RPM flow). The inlet housing is also different and has a 2mm larger diameter.

The actual compressor wheel is the SAME as in the K04-001 (The upgrade turbo) *not* the K04-022 (The 225 turbo)

The idea is that the K03Sport improves volumetric efficieny and VW have said that it's basically the ideal turbo for the 1.8T (low end torque, lightning fast spool etc.)

I did a swap myself on my 2000 TTQC, mainly because I found a used one for $150 and I can feel the difference, it's not shocking but it doesn't run out of stream over 5000 RPM like the old K03-035 did

It is a pain in the *** job and you'd probably be better putting a K04-001 on which are sold new for about $720 (on www.vwvortex.com)

RedRoadster

just not the TT. 150hp TT was sold all over Europe though, not just the UK. It's not too bad at all.