: concerns that one has when buying an exhaust are... : a) construction materials... stainless steel vs. aluminized steel. some exhaust systems are stainless all the way through; whereas, greddy and hks are stainless mufflers with aluminized steel piping.
some HKS don't have the SS mufflers - HKS D1 Turbo and HKS R2 Sport. They have the chrome tips, but the muffler itself is aluminum. The Hipers have the SS mufflers.