Anyone who has followed the aftermarket automotive performance industry for long enough can tell you just how dramatically it has changed over the past few decades. What once required mechanical tinkering and a lot of know-how can now be done in mere minutes via an electric control unit (ECU), which can extract significant boosts in horsepower and torque from naturally aspirated, turbocharged, or supercharged engines.

In some ways, though, the process has become much more difficult. Just ask Alabama-based Audi Performance & Racing, more prominently known as APR. As modern vehicles become increasingly software-driven and OEMs continue to tighten security, the company has had to work harder each year to offer ECU tuning that delivers more power while staying within factory parameters for overall reliability. It’s a far more arduous process now than it was in the early aughts, when my own B5-generation Audi S4 was still fresh on the market.

I recently spoke with APR engineers to discuss the transition and learn more about the fascinating history of ECU tuning—including why unlocking more boost, advanced ignition timing, and other performance gains once felt more like entering a cheat code in a video game. Simpler times: people have been modifying engine air/fuel ratios and ignition timing since the term “automobile” became commonplace. The early hot rod and muscle car eras stand out as high points, as do the early days of turbocharging.

Fast-forward to the ’90s, and aftermarket tuners were routinely cracking open an engine’s computer, removing the appropriate memory chip, inserting it into a reader, and writing lines of code to a new chip. From there, they could make the changes they wanted: letting the turbo (or turbos) build more boost before dumping it all out the wastegates, adding fuel to accommodate the extra boost pressure, and more.