ORIGINAL: Hobbsy
Roto, always set the LS needle with the HS needle at peak, the two needles effect each other somewhat, peaking the HS needle eliminates one variable. Plugs won't cure a poor needle setting.
I can say whenever I tune with the glow driver on and hit the lean side the plug is instantly trashed . No more smooth idle for me , I burned up about 4 plugs doing this ,there is really no need to use a glow driver to tune the engine IMO.