My bajaboard helix 4x

Hello im new to the forum and appreciate any help for my goal to improve my offroad monster currebtly allowing me to cruz deep dune sand at around 14mph top speed, i am in the look for switching to bigger motors and bigger battery anyine here can recommend me what i can do in terms of proper motor ( trying to keep mysekf at 4 motors for AWD) and proper batteries

https://images.app.goo.gl/BoPJxW2eHabDKREr5

This is how it looks, featuring 11 inch tires… on concrete it reaches 43 mph top speed but on the sand it gets stuck doesnt go past 14 mph…

You will be very limited by all the rigamoroll. Unless you machine and such whatever is necessary, then it is a rats nest of uncertainty. And once you start modifying, there will be likely no turning back. Perhaps some specialized tires that float over sand and snow.