I haven't installed Dougs Headers yet(Iam laying in a hospital bed I will when I get out), but from the beginning to the end of my car I have learned a couple important things:
Every part fits differently, especially different brands.
and when they say fits perfectly, no modifications for a firebird they're wrong.
Almost every header I have seen for Firebids, Camaro's, and Novas have problems with the steering gear.
My family has 3 of these cars and our solution: a BFH used WISELY. I emphasize wisely.