My experience with Diesel cords has been weird...
I had the Zathan 40C Grey cords, 31x33 I can't remember who I sold them to on here, and they stretched about an entire waist size it seemed.
So I tried the Zathan 40C black/brown cords in a 30x32ish... I was able to get about 1/2 inch out of the legs wet stretching... but nothing in the waist. These things are so tough too it's insane.
The grey ones STRETCHED. Went from A tight 31 (perfect for me) to a very loose 31, almost 32.
Then I got some Zathan 31Ts from last season and they seemed to maybe have some give but I never found out, they got jacked in the laundromat.
Sounds like those old school ones with the streaks are similar to the black ones though. I had the Ravix in the same wash (can't remmeber wash) a long time ago, the slightly greenish grey ones. Those barely stretched at all...
Good luck man.