I bought some Flo Tech headers from Supershops when they went out of business for $50. They arent the best headers, but they have thick flanges and only had to dent in the steering gear box area since the tube rested on it. Engine torque finished the dent after installation. I have taken them off and put them on at least 5 times in a 3 year period and it is definately a "science". It is almost like memorizing the torque sequence for a ford 3.8 liter cylinder head
I think it took 6 hours to do the first install, but had it down to 30 minutes per side the last time around. Hind sight being 20/20, I would have never bought any headers knowing that I would have to do the job this many times over the past 8 years!