JaredR: will let you know if i find the 850 articles in my automotive archives. recently went on a cleaning binge and threw out a bunch of stuff, but pretty sure kept the 850 stuff. If i find any of them will let you know.
The Ferrita on my N/A car has a low pleasant (g)rumble up to about 60-65, above that it gets a little loud for loooong trips. Anything beyond 1+ hours @ >65 becomes annoying. By now Im sure whatever sound deadening Ferrita put in the resonator and muffler is long gone.