Onderstaand verhaal las ik op een engelse site: This simple, yet effective unit will help boost the power output of your Bmw z3 engine, without sacrificing reliability or comfort. It consists of a small electronic resistance device that is inserted between your Bmw z3 air sensor and the ECU. This is also know as a 'piggy back' device as it is external to the main processing unit (the ECU). You will feel the gain instantly, no fooling around or expensive tuning necessary. Our Power Mod fools your cars computer into thinking that your carss engine is sucking in air at a lower temperature, hence the timing is advanced. Timing advance helps produce more power by igniting the sparks sooner, providing more time for the fuel / air mixture to burn completely, increasing cylinder pressure, thus providing more power. Het verhaal klinkt aardig, maar ik heb er toch mijn twijfels over. Het kastje kost overigens 5 pond.