Headers aren't that bad to install. I've done it several times myself. Just take your time with it, and make sure you have someone to run you to the auto parts store if necessary. It will take most of, if not all day to do it.
First, soak the exhaust manifold bolts the night before with liquid wrench. This will help insure you don't snap one off when removing them.
Jacking up one side of the engine is very common in header installations. YOU HAVE TO DISCONECT THE MOUNT ON EACH SIDE! A floor jack and a piece of wood (small piece of 2x4) against the oil pan is what you'll need. I'd raise one side only at a time if necessary. The passenger side according to the directions. Don't be surprised if you have to do the drivers side too.
You may even have to remove the steering shaft that goes from the firewall to the steering box. Various sensors sometimes need to be removed too to prevent damage while installing the headers.
The factory gaskets are metal and are very good. Stick with re-using them. Be carefull not to bend them or crack them. With everything removed, including the gasket, stick the header in place, start one bolt on each end of the header, and then slide the gasket in between the header and the engine. The gasket will have a spot on each end that rests on top of those bolts you started on each end that keeps them in place (keeps it from falling through).
Another pointer: after several days of driving (several heat cycles), you will need to go back and re-tighten the header bolts. All of them, even the ones on the collectors. You may have to do this a couple of times, or else you will have leaks.
JBA makes nice stuff. Before you start though, make sure the flanges (surface the mates to the engine) is nice and straight. Use a straight edge to check. If they are warped, or not flat, you will have exhaust leaks no matter what.
PS - Buy yourself a pair of Mechanix gloves. You're knuckles will thank you. Lot's of sharp stuff in there.
