Does anyone know if the stock 2013 Fit Sport stereo has pre amp hook ups in the back of it? Like to hook up an amp/sub without buying an aftermarket stereo.

 

No, it doesn't have any pre-amps.

But you don't need an aftermarket just to use an amp... There are adapters/line converters you can get.

That being said... An aftermarket HU would produce a better source to begin with. That alone is worth replacing the HU, if you actually care about audio quality, and not quantity.