The TDI injectors are designed for a much higher pressure from the pump
before they "break".  If that break pressure is lowered by decreasing
the spring shim thickness to, say, the 1.6 TD requirement of 155 bar,
for example (do they even adjust like the 1.6/1.9 injectors?), the IDI
pump would not be stressed beyond its design.  The TDI injectors have a
two stage injection, and I'm not sure that they would operate correctly
after the break pressure is lowered this much.  Also, the mist from the
injector would not be as fine, so the efficiency and emissions would
likely be altered.

-Dana-

> Basically a TDI will run on any diesel pump, 1.5, 1.6 or 1.9 turbo or
> non.  The question is can teh pump handle the pressure over the long haul?
>
> What i would be asking before i plopped down my money, is what pump is
> being used?
>
> If its a 1.9 IDI or 1.5/1.6 pump, i'd just skip this one and buy any old
> TDI and use my own pump. Additionally this would make the engine cheaper
> than an electronic TDI as those TDI Pumps are a big ticket item! (assuming
> they sell the tdi pump and dont give it to you.)
>
> If it is a hybrid pump, the best way to do this from my research, then it
> is a mechanical pump with the beefed up TDI internals to handle the higher
> pressures. therefore, it may be worth paying them to avoid having to
> experiment with timing etc. on your own. But the standard TDI injectors
> work fine with a mechanical pump, the main electronic thing is the pump
> timing, and with mechanical timing set appropriately, there is no reason
> on earth why it wouldnt work.