I'd say the process was long, simple and arduous, with no gaskets torns, no head studs snapped and no exhaust rattles or leaks.

In installation order:
- it was cool to get my Greddy 4-2-1 SS header via UPS; it looked good on my carpet
- it was fun disassembling the old header, with the ugly heat shields and heavy 2-piece construction
- it was fun using the copper spray-on gasket on a new exhaust manifold gasket. It looks like I could have re-used the old gasket, but if you've already spent the money on the header, another $5-10 for the gasket is an easy buy.
- installing the 1-piece header was annoying. The header kept hitting something as I was pulling it up from the bottom. I needed another 1/4" clearance at one point. I removed a couple bolts to get a little flex in the fan/radiator. I'm not actually sure what did the trick. I just kept jiggling and trying and eventually the header cleared.
- here was the biggest PITA: I mounted the header on the exhaust manifold bolts, and started installing. Then I went below, and couldn't get the header mounted on the lower bracket (on the A-pipe). It just looked like that lower bracket -- which is attached to the header -- was wrong; did I get the wrong header? The secret is to loosely install the header on both mounting points simultaneously: both the exhaust manifold bolts and that lower bracket at the same time. Trivial to do if there's two people involved; a little harder to do solo, especially after you've been holding the header in place for a little while
- I replaced the stock cat during this install; that was way more annoying than the header; with the stock cat in my 98GS-R sedan, I had to deal with the two O2 sensors that did not want to come out of the old cat. Finding where the O2 sensor wires disconnected was an adventure.
- use lots of copper goop gasket maker at the header/cat junction.

No runs, no leaks, no errors.

I'm glad I did it myself; makes me appreciate what I did when I look inside the engine bay.

Good luck!