Synthetic polymers and Carnauba wax are basically incompatible; I would lean towards cleaning the surface before the application as there may also be some adherence / durability problems
~ Hope this helps ~
Knowledge unshared is experience wasted
justadumbarchitect / so I question everything/ Jon
If the carnauba that you are topping has any mileage on it the NXT will remove the rest.
If NXT can remove 9 coats of Zaino ( Mike's last ill-fated demo) and repair and fill the surface marring that was underneath, I see no problem with NXT removing a carnuaba lying on a painted surface. JMHO