CVT transmissions are notoriously weak. The lightweight of the Mirage does help, but I wouldn't expect the CVT to handle much more than the stock amount of power. Manual transmissions can usually handle a power boost, but our manual transmissions are also very small. Overall this car is designed to be affordable, not upgradable.
The downside to modern car design, is the engineers can punch some data into a computer, and the computer can tell them exactly how strong parts need to be to last through the warranty period.