I don't know what the issues are. There are stories that there were a bunch of knock offs at one time. My Rb30 has an N1 pump - no issues after about 30,000km including track but my rev limit is 7000 and I don't do do-nuts or any limiter bashing. A local engine builder who does a lot of race engines won't use them so I guess he has had a few failures but I don't know the details.