Pretty much since the beginning the factory infotainment unit was lacking. It worked okay with MP3's on a jump drive, however reception has never been even "okay" as far as I'm aware. (I could be wrong, so don't hold me to it.)
Generally, the solution has been to put in an aftermarket system. Personally, I wouldn't go for bass as the vehicle doesn't have the volume for large drivers, and since it's open-air most of it will be drown out anyway. It's not great as a parking-lot audio showoff either because of the lack of volume.
Rather than put a 10" shallow sub behind a seat, which is going to not be stellar as far as sound goes--think of putting a recliner in front of your home stereo speakers--except it has to be outside where there aren't walls--and while I'm on that, if you set home speakers about 12 to 18 inches off the wall the effective amplifier power is doubled due to "room gain," if you set the speaker up properly in a corner it's about equivalent to 4x the amplifier power meaning "double as loud."
Chew on that for a minute. That means if you have a 100 watt per channel home stereo system and your main listening speakers are in the corners of the room and set up properly, that means your Slingshot has to be putting out 400 watts per channel to match the output of your home stereo. AND, and the sound is
not going to be bouncing off walls and windows, it's going thataway...meaning without building pressure in an enclosed area you're losing a lot of "room gain" as your sound squirts off into space. That's translating into some really big drivers that you don't have the volume to put the correct size box behind. If you have a high-output 12" sub at home, figure you're going to need at least an 18" sub in a 3-foot by 3-foot by 3-foot box. Ain't happening in a Slingshot.
Okay, that's overly-simplified, but it's conceptually why most Slingshot sound systems cost a lot and sound...not so great. Instead, put some stiff mid-bass drivers in paired with good mid and upper-range drivers and you're set. Don't use component drivers, the sound quality is going to be lost due to the environment. Your best bet is a marine speaker setup with matching amp. It won't kill your alternator, battery, budget, it'll last a long time, and it's going to sound as good or better than almost any system out there. In a Slingshot. We're not talking car audio. Awesome home audio isn't easy, quality car audio is difficult, open-air vehicles are, well, if you can make out the words of a song you haven't heard before while driving over 45 MPH without giving yourself a headache that's great.
Now, you know what I said isn't "technically accurate" because, at minimum, I told you it wasn't. But if you grasp the concepts you're doing better than most people, and you're probably going to save a whole lot of money and frustration, which you can put into other mods for your ride. If you want to. I did.
There are
some people who will ask why they should believe this instead of something else. Start here:
This article discusses the relationship between the decibel(dB) for audio devices that produce sound and how we perceive loudness. Basic audio rules are given to relating to the decibel.
www.audioholics.com
The stock radios' in Slings are not good for general radio stations (plus who listens to radio anyways). Almost everyone uses Bluetooth from thier phone or the USB connection. Ride Command 
