BTW those braces are illegal for most classes in autox. Don't ask don't tell?
Lol, apparently 'lightweight body panels' also completely screw you in class selection.

Chassis brace replacement bumps you, too, methinks. (looking it up right now).
Here's everything I could find on subframes. You're looking at at least being in Street Prepared(if I read it right). EDIT: See below.
From the 2008 rules(to be taken as a guideline, only the 09 rules should be taken as canon.)
Street Prepared15.2-E. Longitudinal (fore-aft) subframe connectors (“SFCs”) are permitted
with the following restrictions:
1. They must only connect previously unconnected boxed frame
rails on unibody vehicles.
2. Each SFC must attach at no more than three points on the
unibody (e.g. front, rear, and one point in between such as a
seat mount brace or rocker box brace).
3. SFCs must be bolted or welded, but welding must be to the
OE subframe stampings, not to the floor pan in between.
4. No cutting of OE subframes or floorpan stampings is permitted.
Drilling is permitted for mounting bolts only.
5. No cross-car/lateral/triangulated connections directly between
the driver’s side and passenger’s side SFCs are permitted.
Connections to OE components such as tunnel braces or
closure panels via bolts are allowed and count as the third
point of attachment. No alteration to the OE components is
permitted.
6. SFCs may not be used to attach other components (including
but not limited to torque arm front mounts or driveshaft
loops) and may serve no other purpose.
Street Modified16.1-G. Subframe connectors are allowed as per Street Prepared
(15.2.E).
Modified17.2-B. Chassis, frame, or subframe may be reinforced, provided components
and attachments are not relocated except where specifically
permitted. Reinforcing does not authorize the use of belly
pans forward of the firewall, or aft of the front edge of the rear
wheel opening. It is permitted to have jack points recessed into
the rocker panels, or to have one tube per side extending downward
through the bottom of the door, provided they do not
extend beyond the overall width of the car or in an unsafe or
dangerous manner. No part of the bodywork or chassis, to the
rear of the front wheel opening, shall touch the ground
17.2-D. Replacement of any chassis component (e.g. subframe) in its
entirety by one of alternate construction, unless specifically
permitted, shall result in the vehicle being “in excess” of these
rules and weight penalties and/or competitive adjustments may apply.
...I'm a little lost looking at these. Jay-R Dibble i know ran some events with his braces on, It can't hurt to ask him what class he was in.