I believe that they OEM Fender speakers are 2 ohms. Check yours first. If so, the JL are 4 ohms, and if you just want to swap the speakers, you'll lose a lot of volume. You can add an amp and feed it from the high level speaker outputs, but then you'll be passing on all of the equalization from the head unit that's helping to make the crappy Fender speakers sound decent. To get around that, you'd have to add a DSP, preferably one that interfaces with the optical head unit output.