We just finished calibrating the fuel gauge after a Cgr-30P and C install. The mains are labeled as 25 gallon tanks but they both only took 22.5-23 gallons. We started by fully draining them at the sumps then putting in 1 gallon to enter as empty. I filled 5 gallon Jerry cans with 18.9 litres and dumped them in one at a time entering 5 gallon set points. Both tanks took between 21.5 and 22 gallons after the first gallon. I can see a few percentage points off being reasonable but that’s 10% less. Has anyone else ran into anything similar?