1: About silencer shell type of Silent Hi-Power TYPE-S/Oval silencer for noise reduction. TYPE-H/Round silencer for performance. 2: Main material in the component figure. SUS304/High quality stainless steel. SUH409/Stainless steel commonly used for stock exhaust. 3: About center pipe Diameter of center pipe is the portion that has the largest diameter. (Excluding silencer and tip.) It is the condition with stock suspension. 4: Minimum road clearance between HKS muffler (Any parts included in the kit) and road surface. Therefore, it may be different from actual road clearance of the vehicle. The data is basically the condition with stock suspension. However, please understand that some items have data with low down spring or ride height adjustable suspension kit. Caution: Hook, bracket, stay may be changed without prior notice. ★ Exhaust noise level at idle.