The difference between maximum tested speed and maximum permissible speed for a loco cannot be very large.
See the differences :-
Loco - MPS (km/h) - Test speed (km/h)
WDP4 - 160 - 179
WAP5...
more... - 160 - 184 (for 30086, 200 - 225)
WAP4 - 140 - 160 (official sources say 160, although IRFCA says 169)
WAP7 - 140 - 155
WDP4B - 130 - 147
WDP4D - 130 - 147
WAP1 - 130 (140?) - 160
WDM2 - 120 - 135
WDP3AM - 140 - 160
WCAM2P - 120 - 135
WCAM3 - 105 - 118
WDM3A - 120 - 135
WDM3D - 120 - 135
WAM46P - 110 - 120
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WAP7 locos do have speedometers whose range is 0-180 km/h (probably that's why it's believed so :O) . Well, WAP5, WAP4, WDP4/4B/4D, etc also have the same type of speedometers.