The official word from Suzuki is that its SDTV (Suzuki Dual Throttle Valve) system brings superb response feel, smooth power delivery, improved mileage and reduced emissions. The secondary butterflies do this by opening just enough to provide the optimum intake velocity based on throttle position and rpm rather than letting you decide with your throttle inputs. For example, if you were to open the throttle fully at low rpm on a setup without the secondary butterflies, intake velocity would drop and the engine would not pull cleanly. In addition, the secondary butterflies can smooth the off/on response by opening at a set rateagain, no matter how quickly you open the throttle. And as we’re finding out with more bikes in recent years, in some cases the secondary butterflies are used to restrict the engine’s output to meet emissions requirements. On many race bikes, the secondary butterflies are removed to give the rider more control over the throttle, quicken the throttle response and remove any restrictions. When I raced an SV650 several times, I removed the butterflies on that bike with good results.