After all the reading I have done...I was concerned that my WOTBOX would destroy / clog / wad up my catalytic converter material, so I decided to pull them this last weekend for inspection after having been used with the WOTBOX for a little while.
I would normally post pics or video, but we are talking about looking into the innerds of Magnaflow high-flow spun metallic substrate cats...and as they are no longer new, they are rather dark, so there would not be much to see...so I'll describe what I found and my "upgrades", LOL.
The bottom line is that the epic win that is the power of the N2MB WOTBOX did indeed loosen up the bonding between the driver's side cat outer shell and the inner substrate such that the inner cat material could slide forward and aft inside the cat.
The passenger side was still fully intact.
I decided that my best solution would be to turn my existing setup into a catless setup...so as to avoid the danger of clogged cats and potentially blowing my engine.
So...I used a very long ~ 1/2" diameter masonry drillbit in my Makita hammer drill and drilled many holes through the substrate. Then I used a 3 foot long 3/4" cat iron pipe and pushed it through the middle. I used a small (foot long or so) pry bar to pull the outer periphery material toward the center and then repeated the pipe trick. I also uses dome very long needle-nose pliers to reach in and grab substrate. It took me quite a while...perhaps 2 hours (an hour each) to get them both completely cleaned out.
Since I have decided to keep this midpipe setup permanently, I ditched the ClampCo clamps that were holding my modified "legs" to my cats and I went ahead and welded everything up.
This setup still clamps via ClampCo T-Bolt clamps to my Mac Prochamber, and the other end still has the flared ends that mate to my Mac long-tubes.
I will no longer have to worry about my cats causing a failure. If anyone ever does this mod...(err, destruction) wear quality dust mask (mine is rubber with charcoal filters)...don't just use a dust mask...as the stuff that comes out is a fine powder and I would assume it is rather nasty stuff. I also wore full goggles for eye protection.
So...the car is slightly louder, but not much to be honest. It has a throatier tone now, and - dare I say - I think it might even drone a bit less.
As a refresher, here is what my setup looks like. Again...the T-Bolt clamps are gone and welds are where the clamps once resided: