Whether it is OEM Manifold > OEM Up Pipe, OEM Manifold > Aftermarket Up Pipe, Aftermarket Header > Aftermarket Up Pipe....they all have leaking issues at this connection. Our new gasket solves this problem. At GrimmSpeed we have worked with endless amounts of aftermarket gaskets, none seem to work as well as the multi-layer steel OEM style gaskets. The issue with the OEM gaskets from Subaru is that they are so expensive. Well Grimmspeed has your answer, a premium multi-layer steel w/ stainless steel fire-ring gasket.