I've got one on my DII. I had issues with a couple, but I entered a dialog with Magnaflow and it eventually resulted in their pulling all of the DII products in their warehouse back for testing.
They should have those issues sorted now, at least for the DII models. Some of my other notations prompted their inspection of various models, so it's an improvement all around, at least in quality control.
Be aware that they have historically offered two versions for most vehicles. One version is closer to OEM specifications. That's the one you want. If you aren't sure which one you are looking at, call them and ask.
Be sure to buy from a reputable vendor. Magnaflow provides great support, but it's best to do your part as well, so they aren't backed into a corner on a warranty call. Their dealer network handles most of the process, so only buy from someone you trust.
Be sure your O2 sensors are in good condition and of proper and reputable manufacture. It's common for a vehicle to dislike aftermarket cats, especially higher flow models, but the cat manufacturer can neither control the quality nor the condition of O2 sensors.
Sometimes, you have to tinker a bit.
Cheers,
Kennith
