i don't know what's better, but wouldnt a set of rear air shocks be more expensive than a half decent set of new rear normal gas shocks or oil shocks?
if anything, the rear of these cars needs to be softer, not harder. i have pedders "comfort" gas in the back of mine with stock springs, and it's quite a jarring ride. people aren't real fans of my back seat
if your car isn't a racecar, then it doesn't need coilovers or custom rims. if you want to do stupid shit on the street, then i reckon the best way to do it is on a budget with bolt-in things. forget all this customizing and different parts and turbo motors and adjustable crap crap crap, just get your stuff running nicely and balanced and it will be good enough
hell, i'm kinda getting into making my car decent around a hillclimb track. my "big dream" at the moment is ke70 brakes, a set of rob's old rally springs, some monroe gas shocks i picked up cheap, and some new polyurethane bushes and good steering setup. simple, not cheap and i'm not even customizing anything, and damn effective