For the Mk 2 diesel Jetta(NA) the top speed is 92mph according to my research, so far. I'm sure this is aerodynamically limited as I've found the top RPM is 5000rpm, and according to
Gear Up! if I use 185/70r14 tires, the final drive out of my AUG code transmission and the .75 5th gear from the diesels ACH code trans, 130 mph happens at 4970 rpm. If I keep the gas engine, 6100 rpm, top speed gearing is 155 mph. As I am more concerned with mpg than mph, I'll take what I can on the Salt and be more concerned with driveability and keeping the overall height of the car to the template height that I am building it to(54.5 inches). I do need to use 130mph rated tires for the run, and 65 series tires are easier to come by than 70 series at that rating. Bridgestone Ecopia EP100s at 175/65r14 are the same height as the 185/60r14 original size for my car, and IIRC, are also LRR tires.