I did a fair amount of researching before I bought my oil cooler.
Z1 Motorsports offered the best deal and product that I could find.
Z1 Motorsports 370Z Oil Cooler Kit
Once the installation manual is updated, it will be one of the better kits out there. If your worried about oil temperatures during cooler weather and daily driving, you can't go wrong using the Mocal Thermostatic Sandwich Adapter.