Wadia GNS mods?

Hello

I have seen many threads where a GNS(C) mods have been made on Wadia players......... Can anyone tell me more aboud this GNS mods and what it does, who are modifing the Wadia?

I own a Wadia 381 and are planning to have it upgraded to the i version. If i do the upgrade, then i could also the the mods at the same time..