OK, I've got a Rotec and am running way too much sag in the rear, about 50%. In need to get a heavier spring, but am not really sure how meavy to go. The Rotec, keep in mind, uses an moto-link so it becomes more progressive through the stroke. As of now I'm running a 500 X 2.9 spring. I was thinking that I should up it to maybe a 650 X 2.9 spring. Does this sound about right, or should I even go a bit higher?