I noticed that one of my header bolts is out and when I peeked in, I saw half of the bolt still screwed in and the bolt-head probably flew out...How do I take this out?

 

I would take it to a shop and get them to do their thing. it's too much of a hassle to do, you'll just get pissed off.

 

 

yeh do that NO....take off ur header (after y get a new stud and bolt from a junkyard or something) if there is enough thread take 2 nuts and put them on the stud. Then lock them together if u dont understand tighten them together on the bolt and then tun the stud out of the head very easy to do...if u have the time. Now do the same in reverse. This is very easy to do but i think u have teh 1 peice header which may be a pain to get off so do this at ur ouw risk u can do it good luck