Chassis bracing

[evilC]

I assume that you are based in the States? since Autocross in the UK is competed on grassy field generally and not that much on tarmac. If it is Stateside Autocross it is akin to our Autosolo with perhaps bigger expanses that generate slightly higher speed.
As I now understand the backdrop i expect that you would not want a full multipoint roll cage that will be a pain in the derriere to clamber in and out of. I would suggest that a kafer cup brace is desireable with maybe links back to a crossed braced 6 point rollcage. You may also feel it necessary to take some support to the rear of the motor as it will experience excessive front /rear load reversals under accelleration and braking. Detachable door braces and fixed mid height horizontal braces with connection stiffeners will provide considerable torsional stiffness. What you are trying to acheive is a shell that will resist twisting. To that end it may also be worth bolting the cage to the body shell in an effort to bringing that into play as well. This is usually done at the pillars.

evilC