I can't speak for everyone, but i can confirm the coilovers on the aveo ride just like they would on the VW.

Now the mk2 coilover can maintain close to stock height, but why do you want to change the oil weight? IF you have someone who can do some welding, (to attach the stock end link arm) then go buy some mk3 bilsteins, keep the stock springs, and you should have a firmer more stable ride. Im not 100% sure about the whole changing oil weight thing, I know revalved but the weight of the oil doesnt seem to matter with the size of the valves..

What are you hoping for? the truck reference confuses me.