Looking at a used set, Is there any pro or con as far as longevity or are they as good as stainless marine? Thanks for help

I have a set that I had to send back and have a internal leak fixed..Common problem with them.

SM will out last cmi headers , I have a set that I ran from 94 to 06 on my 509. there still great. my buddy ran cmi e tops they leaked after 3 years. he just fixes them when they leak. I put hardin hurricanes on my blower motor. kind of wish I bought SM gen 3s 5'' instead. hardins are nice but tight fit for me.go SM or hardin=cp