Here is Defi's link to the options they have...
The "sell" imperial quages. Now. does this mean that your local dealer will have them in stock... Ur, maybe. But Defi makes the gauges in PSI. I did notice that the size for the PSI option is smaller. They don't carry many larger than 52mm. But that was the size I wanted anyhow. I plan on puting the Boost on my stearing column.