Stock exhaust material?

I recently picked up a 2013 Double Cab TRD Sport. I was curious about the stock exhaust and what material it is made of. Are our factory exhaust systems made of stainless steel or just some sort of mild steel?

I'm wondering if the exhaust will stand up to all the rain we have here in Seattle. In the past my vehicles have always had rusty exhausts.

Thanks!

 

I'm looking for the same answers--looking at 2014 trucks and found different dealers stating on spec sheets "single stainless steel exhaust". I know that after market adds (Toyota) say SS and lifetime warranty. Just ordered a 2014 and asked my dealer - he said to check with the service or parts dept. I too am tired of rusty exhaust systems I live in N Idaho and the crap they use in the roads in winter are liquid rust-lol