Garmin gpsmaps 541 card

Advise needed please.

Just bought a used boat (2011) and it has two Garmin GPSmap 541 fish finders. Both work ok however, the units do not have a mapping card. Would a mapping card installed in the SD slot provide good detail such as lake contour, depth, structure, road beds, etc??? If yes - which card for East Texas fishing?

Or is it time to upgrade?

Thanks in advance!

I think the 541 has coastal maps. Not sure you can get an inland card such as LakeVu HD to work in that unit.

SE Kansas grass grower

Time to upgarde and het panoptix