yes it does change with speed but is not only noticeable at a certain speed if u know what i mean cos its intermittent.the car is driven hard and as a matter of fact it overboosted the day before this happened and the engine jerked violently 3 times.i swear i heard something fall off the car but im not sure.ive had it on the ramp and all seems fine tho i didnt check the gearbox mounts.shafts are solid.though my mate reckons the drivers side shaft is a bit egg shaped when coming off the throttle?no up and down movement in diff just in and out of the inner shafts.