[radhakr]

As a simple and very unrefined solution you could set the speedboost to cut out lower than 130 so that the fastest you will get with it will be 130 (you will have to experiment to find the cut off point).

I suppose another method would be to reduce their speed by multiplying their velocities by something between 0 and 1 if their speed is above 130, but I have no idea whether this would even work and if it did, how you would decide what value to multiply the velocities by.