I have been custom building exhaust systems for the past 12 years or so for myself. I have done a bunch of them and my personal preference is to completely weld the system together , with the exception of the axle connection, if it has tailpipes and i may need to remove it for repairs.
I have welded flowmasters and dynomax ultraflows with no problems at all. I use mig with er70s(if i remember correctly) and the dynomax are stainless 304. No problems miging to steel pipes after 10 years of driving/ racing.
Now to my question: i’m building another system for my 73 b body, and im trying the magnaflows , which i read are stainless. But, they dont state what grade stainless. Anyone welded these to steel ex pipes with er70s mig?

Thanks.