Guys, I have just taken a look at my 3100 and it definately has brand new head studs holding the heads on. They are all screwed into steel inserts. Whether they are ARP or not I don't know. They have the same black finish and also have 12 point nuts. Regards Dene Collett KR2SRT builder South africa Whisper assembler See: www.whisperaircraft.com mailto: av...@telkomsa.net