can you eliminate the cat on the tdi? Is it tied into the computer through o2 sensors like the gasers ? I am currently running 1992's (have two of them on the road) and have being told I could possibly mount my injection pump on a Tdi when I move up to newer cars making the Tdi mechanically controlled. I have had such good luck with my non electronic VW diesels (started with 1984's), that I cringe at the thought of computers their sensors and controls.
yes you can take the cat off a TDI without any problems. No you can't use your IDI pump on a TDI
I too faced the TDI world with a bit of trepidation.
You can have a mechanical TDI pump (called an "mTDI") that eliminates the electronics, although you would then need to figure out how to mount a different throttle pedal cluster, throttle cable, etc etc etc.
Or... you can accept the electronics and learn to love them, as I have.
I've found the TDI to be an extremely robust system that takes care of itself very well, tells you exactly what's wrong with it when it has issues, and allows you a ton of tuning and tweaking ability from the comfort of the front seat.
The one caveat... like most systems having the right tools makes all the difference... in the case of the TDI you have to consider Vag-Com and a cheap laptop just as important as your set of metric sockets.
As usual i completely agree with Vincent. I found the mid TDI's - like the AHU to be pretty reliable and easy to fix .
The big disadvantage to an electronic throttle is the lag. With a mechanical Diesel you have instant response.