Hi, I have just read the tvpierce message in this thread and I now remember also that the volvo technician when explaining to me why not to have the universal sensor he said that the messages that the sensor sends back to the computer also takes into consideration the ambient temperature around it, so therefore the crimp joint would interfere with the airflow. Also the reason there are two sensors one at the front and the other at the rear, is that the exhaust hits the first one and the computer sorts it out what mixture to provide to the engine, if for any reason due to a not so good or more worn 1st sensor or the cat is not for some reason not as efficient as when new then the second sensor at the rear finishes the job off and is supposed to give the required emmissions. It was my rear sensor that gave all the trouble for me, and believe me in traffic the drivability factor was out of this world and the smell of the amount of unleaded burnt petrol was terrible. While I was waiting to visit the volvo garage I was told to take out the fuses 3 and 5 after stopping the car, apparently when restarting and driving off the engine management system has to reset itself, I don`t know the reason why but it would drive ok for about 15 to 20 miles then be a pig to drive with the black smoke again. Any way after all this I think you have made the better decision to go VOLVO.
Regards