i need to know a few things about shaving and painting parts

i have a cobra rear bumperthat i want to shave how would i go about doing that? and is that process reversable

also what is the additive you have to put in the paint to spray plastic parts, b/c instead of paying a shop crazy money i want to spray my bumpers and spoiler myself

 

im assuming that you want to get rid of the cobra letters from the bumper? im pretty sure its just bondo or some other filler and you let it dry and sand it smooth with the rest of the bumper. and no, its not reversible. you will need to add some flex agent to your paint for when you are painting the bumper, that way when the bumper moves, the paint wont flake off.

 

what is the flex agent called and can i get it from a local paint supplier? and wont bondo flew out of the lettering?