Kohler had a great product a few years ago when I was still a biomed tech- I'm sure still does.
I ran a 55KW 3 ph Kohler w/ 4 cyl turbocharged John Deere diesel with auto transfer switch that was online in ~5 seconds after power failure. Sat on its own day tank mount which held ~150 gallons of diesel (no road tax for generator fuel- we should have run it more often than the weekly warm-up) Of course it was expected to be that fast since it was backup for a hemodialysis clinic.
