Granite Engraving USing a Chinese MINI CNC engraver!!!

Hello everybody,
I own a chinese Mini CNC engraver 3040 and I want to enter the grave granite engraving business. (I emphasis on Granite not marble, Granite is way harder than marble)
Actually the spindle is about 300w, I know that with this amount of power engraving on a granite is not possible.
My questions are:
in case I go for an upgrade; changing the spindle with a more powerful one + using a diamong bit, would it be possible to do the job?
If yes how much power is needed and what bit do you suggest?

I hope to get an answer as soon as possible.

I think you'd quickly kill that little router trying to engrave granite deeply, as is usual for gravestones. It's not just a matter of spindle power; you need to use water to keep the tool and stone from overheating and to control the dust, but that makes an abrasive slurry that will get into the moving parts of your machine, if they're not well-protected, and destroy them.

A better approach might be to use a drag-knife to cut rubber masking for the stone, which won't hurt your machine or require a bigger spindle, and then use abrasive blasting to actually remove the stone to the desired depth. This would be a lot quicker as well as easier on your machine.