I use a mix of products. To start, I apply the surface activator from Sylvania. I mention this because it was pretty amazing to see the ‘yellow’ melt away in the spray runoff. YMMV, but it worked for me.
Middle steps are the typical wet sanding, 600 through 5,000 grit starting by hand, then with small DA sander and hand touch up as required, then a final pass with the surface activator using a clean rag. Then a pass with a tack cloth immediately prior to final finishing.
Regarding the OP’s question, for final finishing I’ve had really good results with the SpayMax headlight system. It’s a 1k primer with a 2k (catalyst) top coat. You are supposed to use the primer followed by the top coat. Spray Max does not recommend using the 2k without the primer. Lens damage, bond promotion??? Who knows.
I used both per the directions.
Make sure you have an appropriate, real deal paint respirator and ventilated work space. The 2k paint can be deadly.
Final result after polishing. The yellow-green tint on the projector lens in the pic below is just a reflection of our trees, The lense is perfectly clear. Note the ‘u’ shaped smudge on the inside of the lens. It’s discolored from heat I guess. Nothing can be done without taking the light apart. It’s not that noticeable in person.
Here’s a pic after the 2k coat, prior to final polishing:
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