2005 325i Auto
No problem at all.I'm with Ray on this one. I'm rebuilding an an engine from another make and was reminded while cleaning the head's carbon deposits how crazy difficult it is. I even returned a pricy gallon of the legendary Berryman's carbon cleaner and discovering that like Compound W, Oven Cleaner, and Rachel Welch, it's not like it used to be when it became a legend. Watered down. The only way I could see any compound cleaning your cats would be if you ruthlessly flooded the engine to near stalling with the product so it's splashing through as a wet mist into your exhaust system, and then I'd be worried about the grundge it's moving from the exhaust manfolds that is now flowing like lava to your already clogging cats.
I know you only wanted to hear from folks who've actually tried it, but thought it might also be worth hearing from folks who have been in the next lane over from the " cleaning with chemicals lane" with a wire brush in our hand that grasp the magnitude of that work and the truth of it working. Many people lay claims to things working online because they've become mentally invested in it since they did it, and if they hold their head just right, and the lighting is perfect, and the only second opinion they got was their girlfriend - that paint job they did in the garage looks "super dooper awesome, man - you should try it!..." Cough...
I'm not one for psychosomatics, so it'll need to work for me to say it does.
I've made up my mind not to try this.