i have a hole in my exhaust and feel that it may be affecting my gas mileage and power. i have a '94 900se turbo. i also have been getting an intermitent cel on my O2 sensor. do you think this is related or is there something else wrong. i just replaced the O2 sensor a year ago and actually have even taken it out and cleaned surfaces to make sure there is good contact. my car runs very rich too.