Be fascinating to hear more about how that actually works; or is it a fabrication by police or drug manufacturers? What mechanism of action would a bunch of metal and exhaust particulate possibly have to produce drug-like effects?
The article does suggest that bombé is made from conventional drugs and basically cut with converter residue, so perhaps the residue slightly modifies its chemistry. Or it might do nothing at all; I'd be surprised if there's been a blind study comparing the effects of bombé made with cat residue to the same made with, say, clay.