I am not sure you will gain usable volume by using a string that gives higher signal output. Most amps have a preamp gain adjustment that compensates for variations in instrument outputs levels do to variation in pickups, strings, wiring, etc.
If you have an amp that need more input signal, you may want to look into an effects pedal that boost signal level. Especially if you are considering Pyramid Flats. I think they are pricey.
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