I have a friend that has just tuned his GTTDI PD130, 2.5" boost pipes, FMIC, EGR delete, full stainless c/w DPF delete and a high flow panel filter. Standard mani, injectors & internals.
He sent his PD130 turbo off to P/X for hybrid PD130 turbo to a place called GP tuning - near pontefract iirc, the px'd hybrid turbo cost roughly £500.
Straight swap on the mani as its the same shell, had it custom mapped at CC tuning in burton and made 230HP 300ftlbs @1.8 bar, this was tuned down to these figures for more traction (FWD mk4 golf) and reliability.
Having been in the car and seen the dyno chart - linear for both HP and ft/lbs like a petrol car, Its frighteningly fast, has hardly any lag and pulls to the redline with no fall off of Tq or Hp.
Everyone RAVES about dark side - yeah they're good but they need to be for the price of their turbo kits, ill admit id was keen to go visit them and fork out some cash for their kit but after seeing firsthand what can be built at a fraction of the cost i think I've been swayed to have a good look into going down this route!
Re; 1.9 tdi / 2.0tdi - yeah the 2.0 is 170 and the 1.9 is 150 …But you've not got the worry of the injector issues on the PD lump and they seem to be pretty bombproof IMO whereas the 2.0 is not so much IMO / mechanic friends opinions.
