Well, we're all sitting here babbling along. I checked the part #...
409 it is. My mufflers are 409, but also a complete 40 series knockoff, at only $45 a piece. So I didn't expect a lot.
The heat, and conditions where you live must have got the better of them. That's terrible, those are not cheap.
I could understand 409 in some turbo applications, but no clue why manufacturers would use it for the reasons stainless is sold. You take a little weight, to have less rust. The same rust, with more weight is kinda...huh.