Paint Type for Respray

[sepans]

My S3 coupe renovation has now reached the stage of a respray. I have read some old posts which confirm my belief in that you need good preparation, if you want good results. One of the points raised was to put a flexible additive into the paint, like what is used on the bumpers of modern cars. Has anyone done this? If so what is the result? Names of products used would be helpful.
Cheers
sepans0(Brian)