anyone familiar with Gemini exhausts?

Just recieved my first Kz1000A1 after selling my MkII in 1989 and it is wearing an unfamiliar 4-1 exhaust by Gemini of Corona, Calif. the collector is huge with a 2.5" OD and ends with a round short Yosh type can that is louvered inside . I'm familiar with most of the aftermarket stuff for these bikes but have never seen this, if any of you guys who older than me (36) remember these from back in the day give me any info you have. thanks

if I remember right its a mac with an aluminum can.