Montana 700i - Any way to use Google satellite images

First off, you should check to see what resolution you requested when you downloaded the BirdsEye images. You specify this on the download page for the new tile, via the Detail setting (standard, high, highest). The higher the detail level, the larger/slower the download. I suspect this also affects rendering time when viewed on the device.

You can also adjust the brightness of the displayed imagery, which might or might not help. Map page > hamburger menu > Map Setup > Configure Maps > top the enable/disable tile for BirdsEye > select brightness when enabled.

Custom maps are the only option I know of for introducing your own imagery in a relatively straightforward way. The Montana has a somewhat larger than normal capacity for JPEG files in the custom map.

Unfortunately, A recent Garmin announcement that BirdsEye satellite imagery had been improved across the board has turned out to be not very accurate. In fact, many users find their older BirdsEye imagery from a decade ago to be substantially more detailed and clear than the current offering.

I have pointed this out to Garmin and provided many examples, but nothing has changed.