One more header ?
 

After all of the input and advice that everyone has given me about headers for my 90 lx, I think I have decided on the bbk equal length shortys, summit pn BBK-1512. I think these will be the best headers for my stang. The question I have is once I bolt the headers to the head, will the collectors bolt right up to my x-pipe? Thanks.

They should fit just fine, some people have had some issues with them lining there h or X pipe back up, but nothing a little simple tweeking won't fix.

They should in theory. You may have to do some prying one way or another, but it should be minor.