there are three tests 2x quick tick over tests 2500 to 3000 revs and a natural idle all lasting 30 seconds each. if it fails the tester has to do a bet test which is a bit more in depth. ask and make sure he has done this. i have tested loads of cars that have failed normal test but have flew through bet test. and it will
help if you get car stinking hot. cats are more harmfull than straight through pipes untill they reach operating temp.