So I went down the rabbit hole a few times, looking for better music (without a headset). Thought I'd discuss some options, here, although it pertains to any model in general, there's a LOT of solutions I found that are specific to the model I was long to improve.
First, the different years have different factory hardware. I believe it was starting in 2020, they went to 'power band' systems. BTW, if I say radio, I mean infotainment system, I'm just old school. Those stock systems sound much better than the earlier ones, and are generally not plug and play compatible with earlier systems. (You can make anything work with enough fiddling, but different physical size and mounting, electric specs, software) I do not have much experience with power band, other than to say a lot of the annoying quirks I've discovered, have been addressed by Indian.
Second, a lot of the older (pre 2020) parts are getting hard to find. While oem vehicle parts are available, after market accessory add ons are not being made any more.
So-
Discussion 1: easy upgrades
It turns out, the factory speakers are a bit of a disappointment. In fact, the software for the 2016 and earlier, will literally blow the speakers. If you turn it loud when going slow, and have the automatic volume control turned on, it will turn it up, when you go fast, beyond 100%. I don't use that feature anymore, even though they supposedly fixed the problem.
I changed the speakers to Polk DB522. These are much higher wattage, and won't blow from anything the factory amp can toss at them. They sound much better, and are less than $100 a pair. (I have a few factory speakers if anyone wants them. ) The install is pretty easy, and I'd say this would be the go to (except see below) for quick audio improvent.
In these bikes, and I think still in the power band, there is no actual speaker enclosure. The sound just goes where it wants, and more than half is wasted toward the front or ground. Speaker baffles, or boom mats, are foam rubber bits to solve this. Crutchfield has a pair that fit well, and are pretty cheap. (I seem to recall $5, but maybe $10.) The ones shaped like the speaker are trimmed to fit in the mount space, you poke a hole for the wire, and simply lay them in place before you mount your speaker.
These 2 upgrades, for less than a hundred bucks and a couple hours work, produce probably a 20% improvement in sound quality, and maybe a 5% improvement in volume.
Next: saddle bag speaker craziness!
Satellite radio:
I know. I told you I went down a deep rabbit hole...
I decided I needed satellite radio. I was done losing signal, I didn't have enough room for a ton of CDs, and I really didn't have much of a digital collection.
There are a few ways to hook this up. 1) run the satellite radio app on your phone, and BT direct to the Head unit. This was unacceptable, I probably lost cell signal almost as much as radio. This isn't a bad idea for local riding, though. 2) use the satellite receiver unit, and broadcast on an FM channel, for the head unit to pick up. I didn't want to lose sound quality, though. And it wasn't worth buying the only receiver that broadcast BT, especially since I already decided I didn't want to lose sound quality. (See below, though.) 3) hard wire the signal to the Head unit. I bought the adapter that plugs in between the antenna leads, and plays on an FM channel. It is now hard wired and works well.
Now looking into things for the sidecar bike... I discovered they have a new product. I would need a new cradle to mount the reciever, I'd just swap it from bike to bike. They now make a BT cradle that's something like $2 more than a plain one. A little research, and I discovered I was way off about sound quality. BT actually can broadcast, about 3x more sound quality than satellite radio does. (Yes they have a lot of bandwidth, but they use it for 200 channels, not quality.) I also discovered they have a USB power converter. Using the USB plug I was going to install anyway, and ordering the right cradle I was going to anyway... I could have satellite radio into those 45 mm headset speakers Rick likes, for less than $10. I also found a waterproof case for the reciever for $5. Now all I need to do is get the new handlebars on, so I can mount everything! And maybe later, an amp and a pair of JL Audio speaker pods...
Waterproof speakers:
I thought it might be worth mentioning, what some of the criteria I was looking for, were. I wanted a waterproof speaker. Several people claim it's not needed, and they ride the rain. I decided waterproof was a must, I didn't look at any others, even if it wasn't needed. With the modern space age materials, it really doesn't change the sound like they used to, it just makes it a tiny bit more expensive. The nearest I can tell, speaker cones are already made from waterproof poly plastics, they just seal the drivers and electrics. Marine grade, means waterproof and salt resistant. Not something I really need, but again, most probably already are, just some are tested and certified salt resistant.
I wanted to get a system loud enough to hear with an open face helmet at speed. This really isn't that loud, so I wasn't aiming for rattling windows. (Although that JL Audio system probably could have.) While I was looking at a lot of variables, I decided somewhere between 200 and 400 watts would be my goal.
The small fairing mounted Polk's were perfect. They fit well, and had (I think) a 300 watt rating. There really isn't much choice in those odd sized 5 1/4", the price jumps quickly. I was lucky the cheaper ones actually did sound so good.
On what was to become the main speakers... I stumbled onto boat speakers, usually mounted in a pod on an overhead rail on a speed boat. Apparently, there's a whole market for this sort of thing, and there's a ton of choices in great waterproof gear. The nice thing here, was that I wasn't limited to a specific size, especially an odd one. (Yes, they're standard size, but almost no one uses them. Most people skip from 4 right to 6, and if they want something in between, they use 5, not 5 1/4.)
Of course, the tweeters were basically only added to the design... Because I had a hole to fill. There also isn't very many small speakers that are waterproof. Of the 2 crutchfield carried, I liked one and got that. Some crossovers were eventually going to be in the mix. If you don't know, those are basically frequency filters, that cut out bass frequencies from going to your tweeters. No sense using power to pump noise that can't be played there.
The Indian aftermarket speakers- those are pretty decent for the money. They're coaxial mid range and tweeter together, with built in crossovers, so you get a pretty decent sound for a small package, and not much money. They're not big enough to do thumping bass, but I didn't want that anyhow. When the decision came to use these... I knew it wouldn't be as loud as the system I was trying to piece together, but it be would nice. I jumped on it, a lot of that has to do with it being half the work to install.
When I finally cranked it up, I listened to the one song I always go to for audio quality... A digital mixed, digital mastered, digital recording of Tchaikovsky 1812 overture. It brought tears to my eyes by the time the cannon were firing.
I also tried the 45mm headset speakers. They work well, I just prefer regular ones.
Saddlebag speakers:
Most commonly, the extra added speakers go in the saddlebag. You need speakers with covers, various wiring and connectors, saddlebag lids with holes, and an auxiliary amplifier. In the older models, they had round speaker covers (classic) and rectangular ones. I think they're the same speaker, just different covers. You need the saddlebag lids that match whichever you choose. I decided manufactured lids with holes, was better than cutting my own. They have flat parts to mount to, and rain gutters to prevent leaks in the bag, but it isn't too hard to cut holes in the standard lids.
Our service department (mostly Chuck, thank you) informed me the wires and connectors, and speakers, would probably be available, but the lids and amp were unlikely. I found a brand new one on the internet and bought it. I discovered a set of lids from a 3rd party that looked great. I won't use this company anymore... Although they did refund all of my money, I suppose they're not horrible. I decided I could wire in the amp using factory connectors, which would bring speaker wires all the way to the saddlebag. Then I could splice into that, for some aftermarket speakers.
The holes in the lids were for both 8" speakers, and 1 1/4” tweeters. They actually recommended a speaker I ended up buying, a 10" JL Audio that fit in an 8" opening. This monster, some resistance calcutions to add a resistor so i don't blow speakers, and Rockford Fosgate tweeters, they fit nicely in the lids. $1500 worth of speakers... I might need to add another amplifier, I think it was only a couple hundred watts per channel... Lol
After figuring so this and having it mostly fit, without paint, I went to put it on the bike... And discovered I could mount the speakers, OR the latch, not both at the same time. After calling dirty bird, they explained the lids were not designed for the electric latch. (Yep they actually did have one model without electric... But it used the same housing, they just didn't put any electric inside.) After returning speakers and lids... Thank goodness I got full refund (love crutchfield). I was wondering what to do next.
Then Chuck called, and told me my speaker lids came in! The ones he probably couldn't get! After buying the matching speakers and a connection kit, things went in very easily. Lids even latched! :) This went as easily as the 2016 upgrade, after that. (I might have had Spartan do the labour on that one, I forget.)
I guess the bottom line is... Make sure you have all the parts, and they actually work, before you cut any holes! Luckily my failure was mostly just a PitA, not any permanent damage to the bike. The 6 1/2" square speaker I ended up with, would fall right through the hole for the 10" I started with.
I changed my speaker too. I put the Hertz speakers in, and I have to say, they sound pretty good. But I don't listen to them anymore. I now have a set of 45mm JBL speakers in my helmet, and they are awesome.