Wanted to share…
I put in new SS downpipes last summer on my 88 V12. I replaced the original tall bronze helicoil nuts with new of the same. But as i was torquing, one nut stripped, and another one deformed. Not liking how soft the bronze was, i decided to install with SS nuts and SS lock washers.
Well, since then I’ve learned that SS is not such a good choice for exhaust nuts. They can loosen, and can corrode with the steel studs. The lock washers can also become ineffective from the heat.
So today i replaced with brass nuts and steel star lock washers. These should be good, little corrosion and no loosening. Copper plated steel is also a good choice, but is very hard to find in 3/8"-24 fine thread. Brass is about same strength as SS.
My SS nuts were still tight, but i did see slight corrosion with the studs. I was able to get nuts off, but there was a bit of resistance after only 8 months.
I used anti seize (now and last summer) and torqued the brass no problem to 18 ftlbs. (Supposed to be 25 ftlbs dry)