Z1 just released a new undertray for 9-14 Nismo cars, that has a nice air inlet in the front, and air relief fins under the oil pan, which should help to move more air on the oil pan and help move air coming through the radiator. I just bought one, plus, this one will work with the CJM oil pan, as the service door is the whole section, so works with the drain plug on the opposite side!
https://www.z1motorsports.com/z1-pro...rm=ProductLink