I'm trying to have an Innovate LC-1 wideband bung installed in the stock downpipe by a friend is an amateur metal worker. The LC-1 came with a mild steel bung.

My welder needs to know the gauge and type of metal that the downpipe is made of. I think it's stainless steel (not 100% sure on that, please correct me if its not), but I have no idea on the thickness. Can anyone help me with this?

The reason for this is because his Mig welder is pushing its limits at 120 amps and welding to stainless might not be doable unless he can somehow squeeze 130 amps out of it. Also, if its stainless, I'll probably want to get the stainless bung, as well.

Thanks!