The California Air Tools 10020 compressor is marketed as a quiet compressor, but as stuff wears out, the compressor gets loud. To improve it, safety couplers replace the originals and the unloader valve is muffled. Empty to full cycle times reduces to 123s from 330s. Sound levels reduce so that it’s practical to work in a small shop without hearing protection.

Inspiration for the improvements are form Kamtechnik’s examples: 1 and 2. Also, improvements by others to consider.

Product links (Amazon Affiliate links):
CAT-10020C air compressor
Milton M-style safety coupler
Air solenoid

McMaster parts
D.O.T. Brass Compression Tube Fitting
1/4″ NPT 21 scfm @ 100 PSI Muffler

Video notes are on Notion.