Ars Technica investigates the evolution of aftermarket ECU (electronic control unit) tuning, drawing on interviews with engineers at Alabama-based Audi Performance & Racing (APR). The piece charts how extracting extra horsepower and torque from an engine — once a hands-on mechanical craft — became a rapid software operation, while paradoxically growing harder as manufacturers make vehicles more software-driven and lock down their systems. It matters as a window into the ongoing "cat-and-mouse" contest between original equipment manufacturers tightening security and tuners seeking more power within factory reliability limits.

In the 1990s, tuners physically removed a memory chip, rewrote its code and reinstalled it to raise boost and adjust fuelling. APR's early-2000s Enhanced Modular Chipping System added its own processor and four selectable engine maps for different fuel octanes, cleverly switched via a sequence of inputs on the cruise-control stalk — the "cheat code" of the title. The author's own twin-turbo 2.7-litre B5 Audi S4 runs such a chip, with maps raising boost from around 9 PSI to 14.5 PSI (1 bar) and factory-rated output of 250 hp and 258 lb-ft potentially exceeding 300 at the wheels on 100 octane. The 1996 introduction of the OBD2 port "opened the floodgates" by allowing software updates through a plug, but by 2008 VW/Audi had tightened security significantly, forcing tuners repeatedly back to the drawing board.