You can easily add 100HP on our cars but it requires tune, 3 bar map, downpipes and meth injection currently. HUGE difference from stock with those things added.
Long term if you want BIG power you can add upgraded turbos and upgraded fuel system and get to 500HP or more depending on if you want aux injectors or not.
How fast do you want to go and the key is how much can the transmission on the X-sport take? My Flex tranny didn't like 600WHP much (torque really).
The path I made is repeatable and so will the headaches at the top end of the power range. I suggest you shoot for around 500WHP, plenty of power for your X to run mid 12's consistently.
One thing to consider is that you have a ton more room at the backside of the motor, have someone make custom manifolds/piping and go big single where the stock airbox is, upgrade the intercooler and do the aux injector scenario. I would suggest you forge the bottom end as well.
Probably get to 1K HP pretty easily but again, transmission won't take the abuse.