Buckhead Import Performance is who found the Magnaflows burned out and clogged up. They were replaced a couple of months ago. Later, one PDX at Road Atlanta (two 20 minute sessions with the motor idling after each with the hood up to cool down), is where I am now with a clogged up cat.
Buckhead has installed and maintains dozens of German FI cars of all levels of prep. They have found out that track time wears out cats at a much accelerated rate - one year life versus 5+ years.
Thus, their solution is to have two short sections - one set with the cat's and one set with either straight pipes or short (same length) mufflers for better sound control. Install the cat's for the annual emission testing and then replace them with the straight (muffler) pipe for the rest of the year. Dozens of their customers have done this with 100% success. Buckhead says that all my problems go back to clogged/burned-out cat's that they were trying to fix with software programming to no avail over all these months.