They are 2.5" front and rear. I have been told the rears have bottom out cups. I will know more this week when I get the unit back and get to open up the shocks. We have already developed a budget/easy add on spring kit for the rear that really softens the harshness and cures about 90% of the kick in the back. The customer we just did one for just came back from a 4 day trip in the Bishop/Tonepah area said it worked awesome. Also did another kit for McKay. I'm sure he'll post his results on here. We will be developing a full-blown dual-rate package soon. I highly doubt the extended and compressed length from the 1000 will be exactly the same.Aren't the rears 3.0 on the Yamaha? Why downsize? You could revavle, or respring.