I haven't had my '04 G35 long - still learning about it. In looking at brake upgrades I see some kits are specifically upgrades for "non-Brembo" brakes. I guess that means my car comes with a Brembo factory option. How can I tell if I have Brembo or non-Brembo brakes? The calipars do not say "Brembo".

you will have orange brembo calipers like these:

You don't have Brembos if the calipers aren't orange and don't say Brembo. Also, if it's an automatic (5AT) you do not have Brembos. If it's a manual tranny (6MT), you do.

yeah unless the previous owner repainted or removed the labels from your calipers it should be easy to tell. like G35fromPA said, the 03 and 04 6mt-coupes came with the brembos, so if you dont have an 03-04 6mt then you dont have the brembos.

Excellent. Thanks for the info. Non-Brembo it is for me (for now).