do chains really stretch?

I'm not sure who makes them... They seem to be decent, and true roller, and the price is decent. The first one I used is with a Comp solid street roller and is daily driven in CA. It's got the 15K on it and so far so good. The owner is a big PSCA racer (Fords making four figures of power) and I'm certain he'd mention any issues that turned up or he discovered. I also did an RB stroker for his brother and althought it's much less miles, no issues.
I want to say the best chain is from Austrailia but the name escapes me...