Some quick calculations:
020 tranny
175/70/13 tires, 3.42 FD, .71 5th, 4500 rpm = 200 kph / 124 mph
175/70/13 tires, 3.42 FD, .71 5th, 4700 rpm = 209 kph / 130 mph
tranny swap: 02A tranny
175/70/13 tires, 3.16 FD, .76 5th, 4500 rpm = 203 kph / 126 mph
175/70/13 tires, 3.16 FD, .76 5th, 4700 rpm = 212 kph / 131 mph
tranny swap, 02A, 5th gear swap
175/70/13 tires, 3.16 FD, .72 5th, 4500 rpm = 214 kph / 133 mph
175/70/13 tires, 3.16 FD, .72 5th, 4700 rpm = 223 kph / 139 mph
tranny swap, 02A, 5th gear swap, next size up tire
185/70/13 tires, 3.16 FD, .72 5th, 4500 rpm = 219 kph / 136 mph
185/70/13 tires, 3.16 FD, .72 5th, 4700 rpm = 229 kph / 142 mph
for fun:
185/70/13 tires, 3.16 FD, .72 5th,
5000 rpm = 244 kph / 151 mph
The design of the TDI diesel is such that the power drops off after about 4000 rpm. The lower I can drop the revs, the more power I'll have, and the faster it'll go.
My dyno'course, the Rabbits have about the same aerodynamics as a brick, so I'm sure that'll determine the limit of things....
-Dave