When I put the headers on I was dropping by rebuilt engine back in so for me it wasn't that bad. If your planning on installing the headers with the motor in it will benefit you to take the two main engine mount to the cradle bolts off and have a jack ready under the oil pan to help you gain some wiggle room. If you car is an automatic it will be a bit more difficult due to tight clearance. Here is a small response to a forum thread. "I just installed some used Mac 1-5/8" long tubes today in my 1994 5 speed. The car has 175K so the mounts are probably collapsed a bit. Here are some notes for other guys that will take this job on some day: The hardest part removing the stock headers was loosening the EGR pipe from the passenger side. A 1" wrench was too big, so use a 25MM. I did not have to disassemble the steering shaft. Both factory headers came out from below w/o jacking the motor up. The drivers side long-tube went into place w/o jacking up the motor. I only had to remove the dipstick tube and the cross member 'brace' (only 2 small bolts). I had to jack up the motor about 1.5" to slip the passenger side long-tube into place. I just removed the transmission mount nuts and the nuts that secure the motor mounts to the sub frame. It took about 5 hours of work to get the stock headers off and the long tubes into position."
If you Google it there is a ton of info out there on this. Do your research and you will save a lot of time installing them.