I would change them
I just broke my rear joint this Sunday. Was going WOT at over 100mph when it snapped.
Messed up the rear floor boards on the passenger side. I suppose it could have been bad from the factory (car has 28k on it) but how would I know.
I was going 65 when I nailed the gas so I don't know if that is worse than a hard launch but I doubt it. Boost was about 20psi or so, maybe higher as I was running Alky.
I am replaceing the DS with a stocker but getting HD U-joints.