I personally haven't done it because there isn't anything out there for a 1992 Ecodiesel Jetta! I'm not familiar with speed tuning, but have heard great things about Rocketchip and also Alligator. Hope this helps!Have information on chipping or Tuning the TDI? Please share by posting here. Where did you have it done? How it's working out for you, pros, cons, etc.