Two questions one about coolant the other about a rattle

SchumiF399

Hi everyone,

I own a 2012 370Z automatic. The car has AEM Cold air intakes with the ETI modules and a Fast Intentions CBE (no tune). I have noticed that on hot summer days here in California my Z will let a little coolant out the overflow tank's tube. The temperature gauge never rises past its normal state and the car does not overheat. I have been wondering for some time if that is normal?

My second question is about a rattle underneath the car. I upgraded my base brakes to the Akebonos 2 weeks ago and in the process of checking the SS lines for any kinks I heard a rattle as I knelt near the front left tire. I searched the forum and found hits for the Manual cars having quite a bit of flywheel chatter. I raised the car and at first the rattle did seem like it was emanating from the transmission but upon closer inspection an listening around with a mechanics stethoscope, I found the source was actually my passenger side catalytic converter. The rattle is only present when the car is warm and below 3k rpm. Sometimes at idle. Could this cat be going bad? If so what can happen to the car?

Sorry for my ignorance I am fairly new to Z platform and this is my first Sporty car.

Isaac