Adhesion promoter suggestions?

Well, I decided to change the color of my car right after blasting it all, degreasing, epoxy and base / clear. Fortunately I am only on the under side and have finished the interior re-paint.

I did a good job of sanding with 320 and very detailed scotchbrighting followed by de-greasing the interior to repaint, but am more concerned about the underside regarding long term adhesion.

Any one have experience with adhesion promoter over an existing paint? The existing is base coat with SPI production clear that is about 6 months old.

I am wanting to go with adhesion promoter after and in addition to the 320 and scotchbright detail. I am going back on with underside with single stage urethane 2k.

Couple pics..

Any experience with adhesion promoter over clear coat on standard rigid panels would be nice. Not talking about fish eye eliminator or painting over plastics..

.