I Know Arrington sells their own, Not sure who makes them, I've seen a few setts and they look good, My builder has used them a few times ...he just shrugs his shoulders and says ...There Main caps.
I have older pro-gram caps in my G3 can't complain .we freshened up the short block this past February after 18k miles and 500 runs and the only marks in the DLC coated Mains bearings was from the Dial bore gauge from the initial build.