I did some offroading (http://jamesbayroad.com/ttr/) this summer and figured out new Volvo springs are too weak for the car heavily loaded (500+ lbs in trunk and on roof). Replaced them with Kilen 66024 springs, which are about 30% stiffer, that cleared some space in wheel arch a bit.
Yes, sway bar affects ride quality: when one wheel goes up on a bump, more firm sway bar does not want to twist as much and, as a consequence, it loads the other wheel as well. Two sets of springs/shocks do not compress as much as only one set, so the car's butt get a kick.







