Originally Posted by crabman
I'm sorry but this is not true. Losing the primary cats will add power making the car something that bmw did not sell and they are not obligated to warranty something they did not sell insofar as the affected parts. While this will end up being a denial on the drivetrain and the power seat will still be fixed a person should be willing to be and financially capable of being their own warranty station before they make this move. An important point when you consider the cost of a new engine or trans for this car. Its not likely to be a problem but if something does go wrong with a major drivetrain component it wont be the dealer that makes any decision regarding the warranty work. A regional rep will come in and look at the car. He has absolutely no mercy, he doesn't sell cars and doesn't care how many bmw's you have purchased. He is very well trained and looking for anything that adds power. A cat delete adds power. When he says no BMW will not authorize the parts or payment for the labor which means you are then out of pocket or you hope that you are such a special customer that the dealer will be willing to go into their pocket for the works.
I would think again, I have fought it in court and won as have many others.
The minor horsepower gain that a cat delete would cause, is the same gain you get when it gets cold outside. He has to directly prove that the removal of the cat caused not only an engine failure, but in your example a driveline failure and there is no link between the two at all. Not only that but catalayic converters, being emissions and not performance based, have their own warranty mandated by the government.