I built a VW Corrado G60 engine pushing out 220whp with a 2.0 litre block (original was 1.8) and no CAT running digifant engine management. It used to fly through the 3.5% CO 1200ppm HC idle test. It always had 0.5% co and 200ppm apart from when the lambda signal wire had broken.
http://forums.vwvortex.com/showthrea...ne-build/page3