It should sit almost all the way up without a rider and then sag a little when the rider is on it, but 5 inches without weight sounds like too much. Are your front springs jacked up past half way? I had a guy that rebuilds shocks and races sleds tell me he's seen Indys that will sag in the back if the fronts are jacked way up for some reason. I have no idea if it's true or not, I had mine about 1/3 of the way up most of the time. I did have mine go soft a couple years ago, the shocks were all ready for a rebuild at that time, but it would still sit up on it's own and then sink too far when I got on it. Even then the stiffener block made a big difference until I got them rebuilt.