Mine runs a Stage 2 Turbo Dynamics and I have had Joe at Chippedire do all the ecu work for me, after some fine fettling I am over the moon, it pulls to the redline with no power let off. The fuelling map in my eyes is set up perfectly, a small amount of smoke on spool up under harsh acceleartion but on 1/4 1/2 throttle there is very of any spool up smoke. Under normal driving conditions on boost between 2-4000 rpm no sign of smoke at all and no dirty bumper. The bonus being a beautiful smooth map, it just feels so much better then I ever could have expected. - To much smoke is a tell tell sign of bad mapping.
Having not driven a TDI 1.9 with a VNT20 based turbo I am not the most qualified to comment, but I did think about going this route but was put off with reading about more lag and lack of useable low down power which for me is what tractor's are all about. Hence look at what BMW / Ford / Jag / Alfa etc are doing with now with twin turbo diesel's; one small for excellent spool up and low down torque with the second larger turbo to hold power higher up the rev range.
Some Turbo Dynamic Specs for you - And remember Turbo dynamics are one of the best turbo builders out there for all types of turbos.
Stage 1 – MD374
Hi flow GT17 compressor wheel, cnc machined compressor housing, 360 degree thrust bearing, cut back turbine blades, lightening of turbine wheel for faster ‘spool up’, modified V.N.T. turbine housing, uprated turbine seals. Other ‘blueprinting’ modifications. APPROX 200 - 220 BHP
Stage 2 – MD376
Hi flow 2275 spec compressor wheel, cnc machined compressor housing, 360 degree thrust bearing, cut back turbine blades, lightening of turbine wheel for faster ‘spool up’, modified V.N.T. turbine housing, uprated turbine seals. Other ‘blueprinting’ modifications. APPROX 240-260 BHP