I read somewhere (now can't find the thread) that you can use P11 RR hydraulic lifters on any SR20 as they are a better design. Can you guys confirm this?

Yeah, I had a few motors torn down and compared them. Essentially, the side oil port (where it sucks in oil) is much larger on the RR, and the top port (where it exits) is much smaller. I would suppose this design sucks in more oil and maintains higher pressure.