you could absolutely make your car faster than both with headers and 3.4-3.6 pulley drop and tune.
i think refreshing the old struts and replacing those old junky bushings and the GMPP handling kit would really wake up that car in terms of handling.
struts would be the biggest factor.
heres a handling thread. it has some reviews of some products you might wanna check out.
http://www.grandprixforums.net/upgra...ion-39418.html