Fred
Your vdi #'s should be the same in both reliuc and coin mode. I can't actually say I have watched which vdi's get disced out at what settings but try this. Lay a nickel, zinc penny (1985 and later) a copper penny (1984 and earlier) on the ground, sweep each coin and get thier vdi. Then start cranking up the disc til you disc out all the coins, thus you have your solution. Disc is good in places but do keep in mind the more disc you use the more goodies you may loose. Using the stock coil I ran gain of 9 disc on 3 coin mode threshold at 9oclock and dug all repeatable beeps, still got some trash but didn't leave much behind, Thats what I like about relic mode trigger in center, set the disc where you want , anything under the setting is low toned all else is high toned, nothing is actually disced out it only has a different tone, I guess kinda like a sound discrimination, which lets you check out all the beeps,high or low and check that vdi for a bouncing 18-20 reading that could be an old buff. nickel or a nice wedding band. Thing about coin mode when you disc it out thats just it, it is disced out. Relic mode still lets you hear it.
Hope this may help.
Ray