FlowTech

used to have them on my duster, they are basicly the same as all a-body headers some have to give them a few dings and others just install them without trouble, the ones i had where pretty easily instaled and didnt need even one litle hit with the hammer:)
just disconect baterycable,unbolt the steering centerlink from the driver side and slide it away over to the passanger side,unbolt engine mounts and lift motor as far as you can without breaking the distributor cap then slide in the passangerside header from under the car (front of car has the bee fairly high of the ground)
after that reinstall the passanger side enginemount and lift the engine again so that it tilts over towards the passanger side of the car then unbolt starter and slide the driver side header in it takes some wigling but it will go in there then before tighetening the headers to the cylinderhead reinstall starter..
that should be most of what has to be done:)

you can use either a motor lift or a floorjack and a big block of wood under the oil pan i like the motorlift better since it gives you more space under the car ;)