A lot of guys talked about the OEM Y pipe and how it has a bad air flow, the Nismo exhaust gives more HP obviously and the weird thing my car when it was stock used to be louder than the Nismo lol and I felt that in two Nismos I drove. So an HFCs with the Nismo exhaust should give you a quieter and better performance than the regular exhaust I saw a couple guys wanting to sell their Nismo exhaust and I know a guy that is willing to change his I don't know if he did yet, but I think he did
