John,
Here's what I did with mine so I didn't have to worry about the rocker panels. I took the sidepipe mounting tabs and bent them so that they would mount on the botton side of the frame. The rear tab lines up just right with a hole in the frame, the front one you could either drill a hole or use a self taping bolt to mount. This way for me made things easier, no messing with the rocker panels.
Also check out this site
Spiral Turbo Baffles
I bought a set of these after talking to a bunch of people who said they are way better. So far here's what I found, the hooker mufflers are junk and last about a year. Mine were stuck in the sidepipe so bad it took almost a week of pounding, pulling, and swearing to get them out. The baffles came with stainless mounting bolts and slid right in, one was just a bit snug but they both went in without any effort. Easy to mount once the 2 holes are drilled. And people I have talked to said they felt a noticable increase in performance.