Mister 4 x 4,
I appreciate the photos with the measuring tape. What's amazing to me, is that on my car, I have stock manifolds and an exhaust system that I had at one time hooked up to unknown origin ( swap meet ) headers. Because I tow with my car as well as drive it everyday, I've always thought I should run a better breathing exhaust, but my experience with the unknown headers was that I crushed the headers within a week of putting it all together, so I yanked it all, put the original stock manifolds back on and had the muffler shop connect the pipes up. The amazing part is that currently, with stock manifolds, I don't have the ground clearance you do with your Hookers.
Now, after looking at yours, and others, photos, I believe the muffler shop must have made up an H-pipe and muffler set up that is lower than stock. My H-pipe on the driver's side only has 4" clearance to the ground, and the H-pipe on the passenger side had barely more at 4 3/8".
Now I see that the FPP and Hooker Comps both have better ground clearance than my current stock manifolds / H-pipe system, so I know my shop made H-pipes are the culprit. Great......Now, I've got to decide weather I replace my entire exhaust system ( need mufflers any way ) with an entire restorer kit with what I believe will have a tighter to the body H-pipe, or take a leap of faith and throw some more $$$$$at some headers. My suspension is stock, and I run 14s for rims, is the car pictured on the rack finished weight? Different diameter rims? Maybe a crossmember to ground measurement would be a better way to compare clearance issues, to know if each car sits lower than another.