1. Upgraded fronts and tweeters to Infinity Reference 6030CS.
2. Upgraded rears to Infinity Reference 6032SI (I know, normal ones would have fit, but already owned a set).
3. Powered by a JL M600/6 six channel amp (yes, a marine amp, it's small and water resistant, good for the Element). Mounted under the driver's seat.
4. Dynamat in all four doors. The doors shut with a "thud" now instead of a "ting", sounds like all the German cars I've owned in the past.
Kept the stock nav and sub for now. The sound is much cleaner, especially at higher volume.
Only issues I have now is that the beep sound from the nav system is really loud, wish I could disable it. And there's some hiss at low volume, think the gain might be up too high on the amp.