Cage is bonded with the Loctite/Hysol 8400 material detailed more here:
What adhesive is used to bond the Elise Chassis?
It sets up at room temp and is an extremely strong and fatigue-reistant 10:1 methyl methacrylate structural adhesive. Detail photos below ore of front and rear hoops at the cage/fram interface. Front hoop is a cap bond over longitudinal frame rail with an "L" that bonds to the "knee" or horizontal frame rail. Rear hoop is an "L" bond that is also bolted to factory bosses. When we made test bonds, the material failed before the bond did and the cured adhesive is harder to drill than the aluminum substrate. I am confident this cage is going nowhere and has nascar door bars both sides, plus it ties into the front and rear shock towers.