It all depends on how low you are running as well. On springs you can run full adjustment on the wishbones and get around -2 degs camber, but on coilovers with no adjustment the camber is around -2.5 degs. The GTi rod ends are ok at that, but I've not tried them with any more camber. I will do some tests when I change the hubs.
The GTi tie arm unfortunately isn't 16mm all the way and steps up to a larger size iirc. I will take a look at this too.