For those interested, I had the cat emptied on my 93 240 automatic. Apart from a great deal of pollution coming out of the exhaust, the mileage per gallon hasn't changed at all. But what has changed is POWER!!! Before, when I would turn on the AC, acceleration would be much weaker. Now, I have a great deal more power available. Accelerations (with or without AC on) are a great deal better. Bottom line, the car is a great deal more pleasant to drive. Don't worry about me, I'll buy a cat right before my 2012 inspection and switch them so I can pass the test. Then I'll switch them back :-)