you need aftermarket springs to support the weight. the SLS holds most of the weight of the rear so the stock rear springs don't actually support the rear of the car. you'll need springs for the 8v. there's no question: you have to have the 8v springs. stock or aftermarket 16v springs won't work. it doesn't matter what brand of aftermarket springs you go with. you'll also need shocks for and 8v. you won't find any applications for the 16v because of the SLS.
86' 190e 2.3L 16v