Dean, when you hear talk of "spun" cats, the exterior shell is usually what is being described not the substrate itself. As master486 said metal substrate cats are better than an equivalent ceramic model for durability. A steel honeycomb structure is more tolerant of heating/cooling cycles and mechanical shock than one built of ceramic. They also work sooner (have a faster light-off) and are less restrictive due to the thinner construction for a given catalyst surface area.
Don't get me wrong, the common ceramic substrates are better these days. In the past so-called "hi-flow" meant larger inlets and outlets. Technology has allowed better flowing ceramic cores. I had Lou's install these on my old SC. No durability or flow issues.
Back in '99 I changed the exhaust on my '92 Sport (long tubes and custom true duals). Per usual I over-thought and over-planned all my options. At that time metal substrate converters were only being used by a few car companies (Mercedes, Lamborghini). They weren't available for retail yet so I had a pair custom made from one of the original manufacturers. Mine had stock cat housings so externally they look like your run of the mill factory cat. The company's website is here: http://www.metalsubstrate.com
. Back then they were starting to manufacture the metal cores for a couple of aftermarket exhaust companies (wouldn't tell me who).
Now you can just buy them from Magnaflow or the place you linked to. I plan to use metal substrate cats when I do the exhaust on the '97.
92 Sport -5.0L
Rolling on 17s, long tubes and a "To-Do" list
97 Sport -4.6L
Rolling on 17s, SOLD but not forgotten
15 Scat Pack -M6
Rolling on 20s... like that means something
Non-Official Parts Hoarder
Cars, guitars, cigars, etc.