as for gases an Argon+CO2 mix at 75/25 although I dont use this mix Argon/CO2/Helium its supposed to be good if excessive heat is required (dont know, as I use the Argon+CO2 only, which is suffice for what I do) mine is a cebora 130turbo(snap-on) There will be people with more experience of stainless with a few good tips probably, I have only welded a couple of bike exhausts


