Thanks again for all the replies everyone ��

The CNC I have is a workbee with aluminium extrusion, it came as a kit form and I built it up.
It's not the most rigid of machines that's why I am cautious about getting such a heavy spindle.

Am I correct in thinking a 2.2kw is close to 3hp ?

Materials I have been working with so far have been wood, mild steel and nylon.
I do have some plans to have a go at some carbon fibre and aluminium in the future.

Maybe I should be looking to upgrade other parts of the machine before I get a spindle like the z axis in preparation for a 5kg spindle.