Lifters and Oil Pressure

Hi Guys. Ok so this has been a while but I wanted to update you on where I got to with my oil pressure problem. Summary is I have a rebuilt 460 with roller cam and lifters and from day 1 had low oil pressure (10 - 12lb at hot idle). I would also get an intermittent lifter rattle that could come and go even mid way driving. Most people told me if you have 10lb per 1000 revs don't worry about it. They often have low pressure. But I was starting to get below that at 2500 revs and above. So it bugged me.
Anyway, after changing oil and filter, checking filter for metal bits, testing pressure at front and back etc, I decided to bite the bullet and pull the inlet to check the oil gallery plugs under there, and also decided to change lifters. My hope was perhaps the oil pressure and lifter rattle were connected. So lifters now changed. No more rattle and in fact engine is much quieter. And better still I now have 40lb oil pressure at hot idle! In gear it drops to about 30lb but still significantly better than the 10 - 12 I had before. Nothing else changed except the lifters. So what were the lifters in there? I'm not sure. They look like "a cheap chinese lifter" (google words not mine). Not Gatermens which is what I was told they were. Next question is why did swapping them out make such a big oil pressure improvement? Honestly I don't know. What I have put in is Comp Cams Evolution lifters. I'm sure someone is now gonna say "WHAT!!!, that's crazy. Why would you put those lifters in??!!". Well I have. After reading horror stories about just about every lifter known to man, I decided to just pick one. So that's what I picked. Anyway that's my story. I hope its useful to someone else out there chasing an oil pressure problem. I just wish I could tell you why they affected it so much. I know it was pushing a lot of oil to the top of the engine so maybe that's why. But I'm still very happy to have resolved it.