YS makes supercharged motors, and their performance is clearly superior in the horsepower category. However, they require much higher nitro content in their fuel, and their needle valve tweaking is opposite to the industry standands. That is....turn the YS needle clockwise to richen the mixture, while the rest of the industry turns the needle counter-clockwise to richen the mixture.
Their fuel tank plumbing is a unique set-up too. The tank is highly presurized by the motor, and there is a one-way valve to be installed properly in the fuel line. So, there is definately a learning curve to get through with YS, but once you become familiar with their operation, you will enjoy top notch performance.