I saw a local Volvo repair shop here in Dallas pre-tighten the rear bushings prior to installation, and because of this, decided to just do it myself. It needs to be bolted up, the car sitting on the ground, level, and I even let it sit for 24 hours and jumped up and down on the front bumper to make sure everything was squared up and at the normal (static) position, and THEN tightened them up. As someone else mentioned if you tighten them prior to installation, the bushing will be in constant stress because I seriously doubt the pre-installation "guess" as to position would be correct. There is indeed a reason the manual states to tighten them after they are loaded (something like that) Just my .02

Scott in Dallas