Yeah,
Dye sub is fantabulous 😀
The only pain in the a**e is that you have to use dye-sub shirts and you are right when you say that they are white or grey.
This is because you are using dyes and you cannot dye white into a coloured shirt.
If you can get to the stage of largeness to be printing material that is then made into say motocross jerseys then that too is dye sub but of an all over nature – if that makes sense 😮
Sounds like you should talk to Monty mate. 😉