From JC:
Short Course trucks are very body sensitive. The proper body style, cut-outs, overall weight and roll characteristics can determine a properly handling vehicle. The SC10 has a very flexible rear body mount which provides several durability advantages but when it comes to performance, having a sturdy base to the body is critical. JConcepts rear SC10 body mount brace performs just as the description suggests and supports the body mount in high-force situations.

While in the turns, the weight of the body hangs down in the rear and allows the body to flex toward the tires which cause unwanted handling and aero changes which may contribute to an ill handling vehicle. Simply install the brace as instructed and the body will now remain in a more standardized position on high-bite conditions and during hard corning.