Steve,

The new radiator cap is actually the same pressure as the old one, just a new and improved version. The pressure rating is 150KPa which works out to around 20 psi. The old version (grey in color) had a tendency to fail early by cracking apart and spewing coolant. The new caps (blue/green in color) are the only ones now available at the dealer, so if you ask for a replacement cap you will get the new version. Even though my grey cap looked perfectly fine, I recently swapped it out with a new blue/green version just for a little insurance.