Hello, I just bought a thicker Koyo radiator for a honda civic si. Will the stock radiator cap work with this radiator? I know a Greddy cap will fit, but for what model? The Nissan or Civic? I have been told that the Nissan Greddy cap fits and have been told that a civic one will fit. Which one fits? People keep telling me different things. The radiator just arrived at my house and I haven't had the chance to look at it yet. I want to buy a radiator cap (if I need to) before I get home so I can install it. I'd appreciate it if somebody who actually knows for a fact would would reply. Thank you.