I do not have any experience with the particular setup you are asking about but I have been a car audio enthusiast for 30+ years and do all my own work. In general aftermarket speakers are designed to handle more power than OEM. The tradeoff is that they are less efficient than the OEM and therefore require a little more power to make the same amount of sound (there are a few exceptions). Adding an amp is usually recommended. More power equals more sound. I donít know how you would go about adding an amp in the fairing, but someone will figure that out and hopefully share with us.
Also, the comment about putting a larger speaker in the factory holeÖ larger speakers also equals more sound. And yes, this can probably be done with some cutting, grinding, and fabrication. From my preliminary evaluation this would not be a project for a novice.
I would love to have the time and money to install a trick high end system on my XC. But alas, at this point itís difficult finding time to ride.