if zzp told you that its because they want you to buy their headers lmao, I bought speedy daddy headers off ebay, yes $250 but then shipping taxes etc. their are 100's of people on this site with speed daddy headers. I wouldnt get any other ebay headers though.
HEADER - STAINLESS STEEL - 97-03 PONTIAC GRAND PRIX 3.8L V6
only problem I had during install was crossover was a lil off but ill take a slight fitment issue over paying $700 more for the same thing. took maybe a hour then it was on, everything else was great.

dont get me wrong zzp is great, I got one of their products on my car, but no way woud i pay $1000 for headers when you can get the same thing for $300, they are even people here selling 100% new ones here for cheaper
heres a link
http://www.grandprixforums.net/brand-new-sd-headers-sale-80732.html