I have touched up bits of my Pearl Interior plastics (they get REALLY yellow with time.) I tried using Year One's 2 part Pearl system- base coat/pearl coat. It took a lot of base coat to cover the darker yellowed plastic. Seeing as how they are not cheap, if I had to do it again I'd first use non-specific white vinyl/plastic dye to get the pieces as bright as I can. White dye is availible in the paint isle of any über-automart. Then, the expensive Year One or other Pearl dye base coat can be used sparingly for merely toning the white, not covering to opaquely cover a darker base.
??michael j Team Chevelle Gold #77
70 Chevelle SS396 4sp, Fathom Blue/White Stripes - Canadian built