I'm not 100% sure if NavTool would work with the base 11 MDX. It is a plug in interface for Carplay folks have been adding to their MDXs for apple or android smartphones. I think you have the option of wired or bluetooth audio streaming with Navtool; along with smartphone navi, Siri, mirroring, back-up cam, movies, YouTube, etc.. on upper display screen. You have to check out the website for NavTool to see if this might work for the base models. It should just be plug-n-play for the Navtool module that sits behind the center console. I haven't seen an aftermarket single/double stereo install for the MDX that looked good or the install caused issues with console afterwards.
The tech and Adv models of the 10-13 MDX have bluetooth audio streaming standard.
Dad - 19 MDX Sport Hybrid Adv Fathom Blue Pearl w/ Graystone
Mom - 18 RLX Sport Hybrid Brilliant Red Metallic w/ Ebony
06 TSX w/ Navi (Totaled Oct/19), 08 RDX Tech (Daughter), 11 MDX Adv/Ent