In the early 1990s, South African Kadett GSi's were further upgraded based on their success in production car racing and initially 500 special units were built as road cars for homologation purposes. This was a minimum requirement for entry into the Stannic Group N races. They went against BMW's 325iS (A 2.7 litre homologation special from BMW). They featured more aggressive 276-degree camshafts made by Schrick with 2 different settings for timing overlap (110° and 107°), revised intake and exhaust modifications (4-in-1 branch manifold and freeflow exhaust), Irmscher spring kit, modified engine management system by Promotec, a limited slip differential developed by Andre Verwey and special Aluett 7Jx15-inch ET35 alloy wheels, they were nicknamed the "Superboss" and held the world record for the most torque per litre (114 Nm per litre) for a naturally aspirated car until 2009 being beaten by the Ferrari 458 (117 Nm per litre). After the first 500 units were produced, many more were built to satisfy public demand.
Power first came from 1.0 L 45 hp, 1.2 L 55 hp, 1.3 L 70 hp and 1.4 L 75 hp petrol engines. (The first engines were all equipped with carburetors; fuel injection came later, but never for the 1.0.) The engines were based on the well proven Family II design, except for the 1.0 L and early 1.2 L engines, which were based on the OHV unit from the Kadett C.
It had some crazy mechanical issues. At one point it stumbled and stalled because the carburetor had come loose from the intake manifold and I had to tighten it back down! Another time, my brother was driving it and the brakes failed. Somehow the end of the brake shoe that meets the brake cylinder piston had become worn on one side, causing the piston to slip off the end of the shoe when the brakes were applied, losing braking and squirting fluid all over.