I guess it depends on the class. If you're in street touring, you can do whatever you want to your suspension (but subframe reinforcement). So yeah, you can. In stock class I believe you have to stay totally stock.
In ST, limited chassis reinforcing is allowed.
Here's the rule, first of all the definition of Strut bar from Section 12:
Quote:
12.18 STRUT BAR
A transverse member connecting the upper or lower suspension mounting
points at the front or rear of the car. Strut bars may be mounted only
transversely across the car from upper left to upper right suspension
mounting point and from lower left to lower right suspension mounting point. A two-point strut bar fastens only at the left and right suspension
pointing points. A triangulated strut bar has a third area of attachment
at the chassis (e.g., at the firewall/bulkhead). All connections to the vehicle
must be bolted. No connection point to the chassis can be welded.
(Transverse= left to right)
14.2 Street Touring, Bodywork
Quote:
G. Strut bars per Section 12 are permitted with all types of suspension,
subject to the following constraints:
1. a 2-point strut bar may be added, removed, modified, or substituted,
but only with another 2-point strut bar.
2. A triangulated (3-point) strut bar may be removed, modified, or
substituted; substitution may be with either a triangulated or a
2-point strut bar. The connection to the chassis (i.e., firewall, bulkhead,
etc) must be in the standard location.
3. Lower suspension braces must be attached to the lower suspension
pickup point locations on the chassis within 2" (50.8mm) in
any direction of the actual suspension attachment to the chassis.
4. Except for standard parts, no connections to other components
are permitted.