They test at 2500/3000 rpm for CO% limit 0.3 , HC ppm 200 limit and lambda 0.97/1.03. Then there is a test for CO% at idle 450/1500 rpm limit is 0.50. My new car was SVA`d at Taunton on the 1st April 2004, the very helpfull tester allowed me to adjust my fuelling during the test using my Laptop connected to the Emerald, I was getting sleepless nights before the test turned out to be a doddle.