Hi Aaron,
Yes the bass did improve - but don't expect a thumping sub like the guy in the car next to you with his dual 12" subs in the trunk. It basically provided a bit richer sound which gets even better with volume. When the volume is at "8" you don't notice it much but crank it to "20" and it sounds much fuller. I also have the balance set to one notch toward the back off center.
My work-order (receipt) from the shop says they "Flash PCM per TSB 18-052-11" which was a software update. I think I read elsewhere in the forums about this TSB (regarding a like issue) but I don't remember where at the moment.
Anyway - its better - not great - but certainly better and enjoyable.
I can comment on this though - when it comes to sound quality and depth - playing a CD is the best and I get good bass from there - playing the radio is ok - satellite is horrible but I don't blame the radio for that. The satellite data is so compressed it sounds like a badly converted MP3 and you will definitely loose bass response because of the compression. I would never pay for a subscription to that service - its that bad. I haven't tied my iPod to it yet but I have used the Bluetooth connection from my Android phone using Pandora. That worked pretty well too - but still not as good as the CD - I suspect some of the same compression issues from Pandora though not nearly as bad as the Sirius.
Oh and I have the 4.3 screen with the Alpine speakers/sub. I wish they would put a separate control for the sub in the equalizer screen or even better, give us at least 5 bands to tweak the sound quality. Then I could crank anything 80hz or below to let the sub do its thing and adjust the others to taste. Dodge?? Are you reading this?