I highly rec. welding in your rollcage. not only does it make your car more solid but safer to.
check out this web sit , it shows me going over turn 3 @ 55 and rolling at least 2 1/2 times stoping
on roof. I walked away with 1 little blk&blue mark under my arm from the seat. After rolling , it wasn't bent and no cracks in the welds
http://www.youtube.com/watch?v=2t44FbOShu0

 

mine