Take ALL the plugs out, alt. off, air tubes from mannys, then go underneath & disconnect the flange bolts, if you have the car up allready on stands (get it high), you'll need a step latter, i'm small, so i sat in the bay area, if the bolts are rusty on the manifolds, they should still bust loose, my car came from NJ (rust country lol) & they still broke loose, i took both side manifolds out through the top, once they are out, you'll see alot better at what your dealing with, then your still about a 1/3 way home from the complete job LOL, but its worth it in the end, just don't get shorty's, you will hate yourself when it doesn't run any better, if your going to stay with cats, go mid's or LT's.
I took my car out the other day, it now fishtails through 1st from a 20 mph roll. & spins on the 2nd. gear shift & there was still some peddle left, It NEVER did this before, Headers indeed wake these cars up dramadically, so take your time & enjoy the end results, Oh, & the new sound is "FANTASTIC"
If you have Qs along the way, just ask.