So a 1/8 to 1/4 adapter arrived today and I finally hooked up a Sparmax Air Tank System to my Iwata Smart Jet. The air tank doesn't make a difference above 15-20 psi.
However, it does make a huge difference below 15 psi. I was able to spray at 10 psi with no pulsation whatsoever for a long time without hearing the compressor. The Smart Jet is pretty quiet, but it felt kind of surreal to hear only the soothing air sound from my HP-CS. The air tank probably will not make me a better painter, but it surely adds to the overall airbrushing experience.
Kudos to the Sparmax HQ in Taiwan to go extra miles to help this modeler in the US!