RPM's A-arms are over 25% thicker around the hinge pins than the stock versions which translates into pure RPM muscle to help eliminate damage during those "Wow, did you see THAT crash!" moments. Other design improvements include angled leading and trailing edges of the A-arms, which help the A-arms transition up and over objects much better than the blunt surfaces of the stock arms.
They also focused on the hinge pin retaining system used on the stock A-arms. Using a small screw hole so close to the hinge pin like the stock arms do weakens the A-arms. They moved the hinge pin retaining screws in-line with the hinge pins, significantly strengthening their A-arms in the process. By eliminating the smaller 2-56 hinge pin retaining screws, we've also eliminated the problem of the hinge pins falling out due to varying screw head diameters.
Their final focus was on slop elimination. RPM's strict quality control allows them to tighten up all of their tolerances without fear of binding the suspension system. The final result is a smooth, free moving suspension system with minimal slop. The tighter tolerances on their A-arms allows other critical adjustments such as camber and toe angles to be much more consistent, providing better and more consistent control of the SC10, SC10B or T4.