It's not even the firmware; it's a codeplug thing.
The low power and high power repeaters have different model numbers. The codeplugs for each model have different power definitions. You can modify the codeplug with the right tools, and then write it to the repeater, and it will put out less power. However, if you try to read a repeater with a modified codeplug, it will tell you there's an error and you must correct it before it will allow you to read. (CPS presents a "click OK to fix the codeplug" dialog popup). To remedy this, you can just keep using the modified codeplug, make changs to it, and write it to the repeater instead of reading each time.
I modified a 20-48.0W UHF 403-470 repeater so it allows for 0.9 - 48.0W TXPO selection. I was using it to drive a 100W Henry amp with about 7W. The modded repeater is very stable and there's no issues with unwanted emissions due to non-linear operation of the PA.
As Motorola has taken an interest in shitting all over our website, me, and anyone else who experiments with their products, I'm unable to elaborate or assist any further. I know it's just for ham use, but they've made it clear they have no souls and hate all of us. I hope they die, too.
Good luck.
