All pkg amp kits come with more than enough power wire but usually only a couple feet of ground.
Anything wrong with using a portion of the power wire for the ground?
Other than the color being same does it make a difference.

 

Wire is wire - same type, same gauge, no problem. Take a black marker and paint it if you want...

 

Thanks, as I figured. Could go get some black ground cut to length, but there's enough power wire in the amp kit to go from the amp to battery probably 4 X.
Thanks