KBS Klean (with some elbow grease depending on the dirtiness of the surface) is the best way to properly prep a metal surface before applying KBS MAXX Clear. RustBlast is a powerful acid etch and RustBlast leaves a dusting of zinc phosphate. The zinc phosphate is a white powdery residue and can cloud a clear coat when the clear coat is applied over that surface. RustBlast also etches the metal surface and can alter the appearance of the metal surface slightly, so when your desire is to keep the look of the bare metal, keep this in mind.
It is best to simply prep the metal surface with KBS Klean and not use RustBlast when applying KBS MAXX Clear with the intention of protecting the metal surface and keeping the look of the bare metal. KBS MAXX Clear is formulated to adhere direct to metal and will have powerful adhesion to the bare metal surface that has been prepped with KBS Klean.
Please read and follow the complete application directions for KBS MAXX Clear --> https://www.kbs-coatings.com/kbs-maxx-clear-directions