09 g37x about 61K miles (after vacation to S. Carolina and Shenandoah nat'l Park). Went to the dealer re: noise/rattle at about 1000-1100 RPM. Sounded like it was a motor mount or bracket vibrating, no biggie. Dealer informed me its the catalytic converter and not throwing a code or affecting emissions. Service mgr. said he would look into getting them replaced under warranty, car is out warranty. Called be back couple weeks later and they will cover it under warranty! Great! Other then the rattle there was a loud buzz occasionally on a cold start that stopped before i got out of the driveway. I suspected it was a converter but wasn't worried about it. Glad its being replaced! cant badmouth the dealer!!

 

Passenger side? I had mine done last year 59k, 2009 G37X also.

 

Cats have a longer warranty. Like 80k miles. Unsure of years. 8-10 I think.

 

Yes Passenger side but they said both were bad and replaced both. hmmm right about the same mileage as yours although i think my was making noise for awhile when cold. I think the warranty is 8 years as long as there is no driver damage like denting. Also they are supposed to be throwing a code for replacement. Mine was not but i am very glad they replaced both. Car is quieter and smoother.