The only shocks available for the aveo are: Oem, kyb gr2 and a monroe which is probably just a relabelled oem
none of these are considered an upgrade for any car, but the kyb gr2 is valves differently than oem. That makes the the only "upgraded" shock for an aveo.
Look at your pricing if you buy lowering spring and shocks you will spend at least $400 shipped and only get marginally better performance over the oem shocks (not really even a noticable improvement unless
your current suspension is blown). For the same price you can have better, to
me that is not an option get the best for your money. Spend slightly more and get weitecs or something and have adjustable dampening as well to be able to fine tune your height and ride comfort in 20
minutes.
But it's up to you. If I was going to persuede you it is coilovers all the way. I have had lowering springs and kybs on other cars. And they road fine, sure. But they are not like an h&r cup kit or bilstiens in quality.
These coilovers don't automatically make the ride better than a matchEd quality shock and spring kit. But there are no matched quality shock and spring for the aveo. So even the cheap coilovers are an improvement over any spring and kyb. But better coilovers would still yeild a better ride!