you still running 3bar of fuel pressure pal? if yes you may have to fit the standard exhaust manifold with pre cat to assist the race cat.
online
1. If a vehicle fails for high CO at idle and /or fast idle then.... if
Lambda is too low, the mixture is too rich. This can be caused either by a
misfire or by a faulty Lambda sensor. If it's running very rich, the 02 and
HC will be higher than normal.
2. if it has a high Lambda and high 02 (0.5 to 1.5%), the "CAT" could be
faulty. Before condemning it make sure its hot enough to work, the Lambda
and other sensors are working OK and the exhaust downpipe hasn't got any
leaks.
3. if the vehicle fails for high HC then ...if the CO passes, the vehicle
is probably misfiring. Or if the CO fails and the Lambda reading is too low,
the mixture is probably too rich and it may also be misfiring.
4. if the CO fails, the Lambda reading is high and the O2 reading is high
(0.5 to 1.5%) the "CAT" could be faulty. Again check out the simple measures
above before condemning it.
5. if the Lambda fails then...if its too high the Lambda sensor may be
faulty, the mixture may be too weak or there may be a hole in the exhaust
downpipe. If Lambda is too low the sensor may be faulty, the mixture may be
rich or the vehicle may be misfiring.