If your uprgading the rear susp. it would probably be cheaper to buy both lower + upper in a kit. I dont know how much "higher" or "lower" it would adjust the car. As far as my understanding it's more of a performance thing, allowing you to adjust the pinion angle of the rear axle. However it may help if your a c*nt hair off on a wheel/rim clearance issue. The stiffer/longer springs mentioned earlier are still the best bet alone, or combo'd with new trailing arms, for fitting fat rubber/rims under the back. Drag racers on this site will tell you they've been fitting almost 28" slicks back there with little to no modifications for a long time. Again as posted before, buy the wheels you want, test fit and then make mods if needed as they should be mild and within a budget.