Yeah, it's stainless. The black is a heat resistant paint that helps keep the rusties away. Not sure about the warranty, even though I have a Remus myself. Usually, though, I don't believe warranties transfer from owner to owner.
<span style='color:blue'>2000 323i Sport Wagon (yeah, I got the wagon!)
Remus Sport Exhaust w/ Ralley Tips
10" Kappa Perfect 10.1
1000w Kenwood Amp</span>