I have installed the onboard air compressor ( ARB CKMTA 12) in my raptor under the rear seat so it is out of the way and invisible, it is also a way to protect the compressor from dust, mud and water.
I tested it on 1 tire and it took about 2 minutes to air up my 35" tire from 15 (what i use offroad) to 44 (the PSI recommended by Ford) which isnt bad i guess

Here are a few pics of the installation and the finished product.
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