It's not exactly a secret. I called up Shimano in Irvine, CA about a year ago, and asked nicely if I could get a Torium anti-reverse dog from the fresh stock. They sent it to me free of charge. The new ones are made of harder alloy, they don't wear out like the old ones did. Other than that, my much used and abused Torium 20 has the Shimano's standard drag upgrade parts, Carbontex drags, ABEC5 stainless spool bearings, and I use two thin/one thick belleville washers in the stack, so it looks like this (().
Oh, and I cut off the line keeper (a.k.a. palm chafing device) and glued the inside half of it into the sideplate. It's one of the best upgrades you can do to a Torium.