One problem related to engine exhaust system has been reported for the 2004 Infiniti G35. The most recently reported issues are listed below.
Evidently there are a lot of problems with the throttle bodies on Infiniti G35 models. I own a 2004 Infiniti G35 which I purchased new in June of 2004. I have 61, 300 miles on the car. My throttle body just broke and according to the forums this happens frequently and is only covered by manufacturer's warranty for 4 years or 60,000 miles. In 3 states it is covered for 7 years and 70,000. If the problem is that common, it should be a recall or covered under warranty for the 7 years and 70,000 for all states.