My '17 Premier does the same thing, XM is way louder than FM or AM. I'm assuming it's mismatched output levels between the two types of receivers built into the head unit and could probably be fixed with a programming change. I'm not much concerned with it because I'm dumping the XM feed anyway when the trial runs out, but I do understand that would be annoying if you're keeping XM.I have a 2017 LT Sedan also (Factory stock) with the same problem. I usually listen to XM 50’s/60’s with volume between 18-20. When switched to FM I have to increase volume to 26-28. First time I experienced this I was listening to one of my favorite 60’s song on the oldies FM station with the volume really turned up, then when I switched back to the XM 60’s station I got sound blasted. My IPhone has the same problem too. Volume on radio has to be increased quite a bit even though it’s in the USB port with phone volume all the way up. Don’t know if this is a normal problem with the radio or if there is a fix.