I have been trying to recall what spec joint I have, and seem to think, that they used the same deep plunge joint that was on the old driveshafts. And that they did say it was marginal for the power. Of course I wont remember that when I call on Monday!
Looking in the GKN catalogue, they do make a heavy duty motorsport CV in that size, but it has only +/- 8mm plunge. Looking at the wear pattern on the one i took out, that should be enough, so i will try the warranty claim in a way that they supplied the wrong joints, so I need two of the heavy duty ones... that is assuming I dont already have heavy duty ones...

Probably wont get anywhere, but its worth a try....

Main thing is the shaft didnt break & isnt damaged!