I have always suspected that the removal of the CAT causes some problems with the accuracy of the O2 Sensor. Although I do not have a answer for you, I'd be interested in hearing your results when you do find a solution. -----Original Message----- From: Jan@xxxx [mailto:Jan@xxxx] Sent: Saturday, June 16, 2001 7:19 PM To: dmcnews@xxxxxxxxxxxxxxx Subject: [DML] Advice on tuning my engine Hello everyone, I need some advice for my car: I had the Cat replaced by a pipe a couple of months ago (which is legal here) to get a little more performance out of my car. This DID do the trick, not much, but noticable enough. The car was behaving beautifully when I got it back from the shop untill about three weeks ago. When Idling you can smell some unburned gasoline from <SNIP>