This topic is of interest to me as I plan on replacing the battery in my soon to be 4 years old '09 this weekend. My preliminary research is to stay away from Optima and that batteries made by Deka are good. I live in SouCal and there are AutoZones everyone. Their Duralast Gold is supposed to be top tier. I am not interested in a low weight racing battery just a reliable, quality replacement battery. Here is the Autozone one that is made to fit the 370Z:
Duralast Gold/Battery (35-DLG) | 2009 Nissan/Datsun 370Z 6 Cylinders 3.7L FI DOHC | AutoZone.com
I'm sure going to check the measurements though before I get home and find out it's too tall for example. Other suggestions or comments ?