168 for definate, but at all weight classes he was faster than 95% of the fighters in that devision at the time.
If the question is: where was Roy the fastest compared the division's elite or average, the obvious answer is 175. His opponents was much slower there since higher the weight class a bit slower the fighters are. But Roy's speed was sick wherever he fought. He's one of the fastest crazy talents I've ever seen on a motion picture.