At 143, it would not be surprising if you were due for a new cat. But plugs and an air filter are certainly cheaper. I would go ahead and to them before your retest, and try getting/keeping the cat hot when you go.
But definitely get the CEL read and cleared before you do. __________________ *Except 318ti 
'97 318ti M-Sport
'95 M3
BMWCCA |