It doesn't make it law....... but a recent report by Consumer Reports indicates that the Wally-World battery is as good as you can get for your money. I have always like and ran the DieHard, which on sale, is a good price and longer guarantee's.
Still, I have two Wal-Mart batteries that are doing very well and the best part is if one goes bad you can now find a WalMart faster than a parts store! (Wal-Mart guarantee is shorter)
....still like my DieHards though!