Why not upgrade your radiator while you're in there? Instead of ZZPs oversized radiator, why don't you get the same thing from OReillys, but cheaper (because of no shipping), local, and a lifetime warranty too?
Proliance Radiator PN: 432387 (Measure it before buying, make sure the core is 1-3/8". Some maybe mis boxed like I discovered)
And here is my write up from yours truely...
Pontiac Grand Prix Forums : Grandprix