Kevin:

I never have needed to use the low boost pump with the IO-550 in my
Legacy.  Since my first flight in August 2003, my engine has always run
the same at altitude as down low, so I've left the pump turned off.
That said, I believe that my highest cruising altitude has been 14,500
feet.

Carl Lewis
Legacy L2K-203
N14CL


"Has anyone been able to do something to mitigate this requirement of
having to have the boost pump on at altitude?"