I slipped the rear header in from the bottom. I didnt have to struggle at all. In fact it surpised me how easy it went in. The trick is to just jack the front of the car up high enough. I drove the car up on ramps, then found some beefy blocks of wood to set my floor jack on to have the nesasary reach to jack the car up further. Then I used blocks of wood under jack stands to hold it up. The front tires never left the ramps so I felt safe. The rear bumper came close to touching the ground, so if you are lowered, put a 2x4 under the rear tires.
This method sounds ghetto (with all the wood you need
) but you need the height due to the attached downpipe. Or you can dig a hole thru your garage floor....what ever works for you......