After adding front and rear 'maro spoilers to my car, the car had a VERY NOTICEABLE difference on the road at 50mph. It seemed more planted, especially the front end. Highly recommended. But then again, that front spoiler is tough to avoid scraping on stuff, and the rear spoiler requires drilling a whole bunch of holes in your trunk lid... so perhaps just adding a cheap front spoiler is the best way to go without taking out the ol' drill!
'68 Firebird, 350-4, 2 spd auto, triple black, Dlx Interior