[n[ate]vw]

I don't know how much faster the motors are, but I have already made an algorithm for reining in some automatic control tests.
bb_man_pot was a pot (sending in the opposite of assumed input) that we used to control the percent of speed. You could replace this with a variable. To only affect positive speed, you could put this in an if statement.

p1_y=p1_y-127*(254-bb_man_pot)/255+127

Keep in mind that it might not be practical to limit your forward speed just so the forward/reverse speeds are equal.