I also have a hard-mounted, 12V air compressor in the spare tire well underneath my truck. I have a 5-gallon air tank that stores air at 125PSI regulated by a pressure switch mounted under the truck as well. The air tank goes into a manifold and has three outputs. Two are regulated down to 90PSI to run ARB Air Lockers in my front and rear differentials (don't have the front one yet, but the air is there for it when I get it!), and to a quick disconnect as a backup air source to the CO2. The CO2 is much faster than the Compressed air. My Air Compressor is a Viair 450H, with 100% duty cycle at 100PSI and 4CFM of output. I can also use the third output to run air tools if I need it