Do Magnaflow's wear out?
Not sure how the warranty works on the magnaflow products but my dynomax come with a "lifetime" warranty as well. Reading the fine print, I would have had to send it back to summit (where I purchased them many years prior) where they would then send it back to dynomax who would then determine if i hadn't voided my warranty somehow, then they would send me a new unit assuming all was well. I had read from multiple sources online that this whole process could take weeks or maybe even a few months. That was longer than I could afford to wait and have my daily driver parked so I decided to repair the cracks myself, which funnily enough voided my lifetime warranty on the spot.
I knew what I was doing, and accepted that I couldn't afford to wait out the whole process of getting my broken muffler replaced under warranty.