I use Ultra on my second car that is less finicky about lubrication, but the GM test does show the RP catches more grit then any other filter tested, even the Amsoil one. I do realize they are made with similar specs from the same lab, yet the RP patch was cleaner. Furthermore, the Ultra are stiffer out of the gate and are not as pliable as the RP filters are after use. I did a 2 year 10k mile oci and cut RP filter open and it was very soft and pliable. I had an oci 1/2 that on the second vehicle with less miles and it wasn't as bad as paper, but nowhere near the RP filter. When just considering the Media, my results of the few filters I have cut open mimic the result on the GM test as far as quality. And the value in this review was he compared it to the wix XP which was the one glaring thing missing from the gm test.
The patch on the right is the contamination running around an engine, RP far exceeded the field in this
GM test. The cleaner the patch on the right, the less contamination that micron in your engine. Synthetic media took all of the top spots, they flow better and catch more grit.
Royal Purple
Fram Ultra
K&N
Wix
I have been using these filters long before I was aware of these tests based on the results I had. Very popular filter among the hemi crowd as well. Guys want to keep those engines clean, and it seams clear to me RP is a great choice for a filter, especially for a long oci. At a minimum, it is worthy of a personal test for someone considering filtration. Do a long oci on your favorite filter, then consider trying a RP once and cutting both open.