I would say weld EVERYTHING. I didn't have that available. I'm thinking about going back and having the brackets welded to the frame, but it holds just fine.
I put the PHB on my car using a 7.2V drill and jackstands. Took two days with such a horrible setup.
Make sure, whatever drill bit they require you to use, that you buy one of those bits that are about 18" long. This is the most important thing I found, it was really convienant to not have to jam yourself under the car to drill the holes with a longer bit.
XBL - ReefBlue
Built on 8-18-1993 exterior-PD, interior-D6. 1 of 1,316.