And/or,
as the barometric pressures changes with passing weather fronts.. If the SG's indicated boost PSI being off in the single digits bothers you guys, let alone tenths of a PSI, then you guys are going to be re-zeroing it almost hourly during even the mildest of frontal boundary passages.
My point is that you guys are chasing an almost constantly moving target (except when a High or low pressure parks itself over your location).
Been a long time since I took my flight exam, but as I recall, a barometric pressure change of 1" of mercury (common US unit of measure) = ~0.5 PSI, check your local weather almanac to see the hi/lo baro range in your area over the last 24hrs, week, month, year, etc, convert the units to PSI and you will get a notion of how volatile your indicated boost PSI variance can be even if your car is parked and stationary. (
www.wunderground.com is a good source historical baro data).
I really haven't studied the X-Gauge coding syntax closely, but I'm sure you can control the numerical precision with a bit mask of some sort (i.e. remove the precision to the right of the decimal. Tenths of PSI ) so you only report PSI to single digit precision, that would make the PSI wander, due to altitude and baro changes, much less apparent.
Another example of why I think boost is really best represented by an analog visual indicator vs numerical.