To add to this, IIRC etching primer and filler do not go together right? Since the etch is acidic or something like thatetch primer is in no way meant for filling scratches, if it fights rust it does not fill, and if it does it will shrink down into the scratches after a few months.
polyester primer is for doing ultra ultra straight paint jobs and or vettes and fiberglass parts, its name in the tech manual is "sprayable filler"
BTW unlimited is known to make the worst fiberglass products on the face of the earth, but after this VFN I'm not sure if anyones is really much better than anotherStrange, my Unlimited Products cowl hood is straight, had it for 12 years now.
It all depends upon the model used to make the mold.