Congrats on the H3 purchase.
I’ve been incredibly happy with my H3. Yes… I to would like to see a few more horses under the hood but it still does a nice job.
I replaced my head unit with an after market single DIN unit and used the Metra 99-3304 install kit. I have some detailed pictures/instructions of my install at
http://www.rausite.com/hummerh3.htm.