I installed mine on my '97 myself, including changing out the exhaust valve springs. Those last 2 cylinders were a major pain, but I understand new valve springs are no longer required. It wasn't a PBRX (didn't replace the exhaust to turbo elbow) so welding required. I haven't welded since before MIG/TIG so I paid to have that done. Also, on the '97 automatic tranny, I had to include a TC Lockup box, which had to be wired in, that was a little flakey at times, but still not hard to install.
I intend to install a PBRX on my '07/6 speed myself and don't anticipate any (much ... too much... great) problems. But, like my wife has learned when I tell her "this should only take X hours, she says "see you in 2X or 3X hours". :)
PacBrake instructions were very clear, detailed and easy to follow.