In my opinion the factory Torana brakes are barely adequate. If you are planning on buying new rims then that would be the best time to make a decision on the stud pattern and upgrade the brakes.
The Engineers Certificate is valuable where a component needs to be tested to destruction. The Engineers Certificate for the Hoppers LX brake upgrade covers the calliper adaptor plate and the stub axle.
The adaptor plate and stub axle were tested to confirm they could withstand a greater force than the force required to induce wheel skid on a 1200kg car. The force required to induce wheel skid on a 1200kg car was calculated be the certifying engineer at 1854 Nm. A stub axle with the brake kit was mounted on a test rig. The disc was clamped in the calliper and a force applied to the disc. The stub axle calliper mount holes fractured and the adaptor plate deformed with a load of 3423 Nm ( 185% overload ). On this basis the conversion kit is deemed to be suitable for the intended application.
The engineer that signs off on the brake kit once it has been fitted to the car can refer to the Hoppers Engineering Certificate to confirm the kit components are capable of handling the forces generated. If the brake kit does not have an engineering certificate then the engineer may request the components are tested to destruction or may be able to compare the components used with components in the Hoppers Kit to reach a conclusion on their ability to handle the forces generated.
The engineer would then need to check the kit has been installed correctly with suitable grade bolts and there a no clearance issues. Once the installation has been inspected, the brakes are tested on the road to confirm the brakes are balanced and measure the braking force generated (G force).