OK I understand. Here we don't have to do annual or periodic tests. But if we get noticed by the police and they find defects then to get the defect notice removed from the vehicle we need to pass tests.
Gotcha. I chose to run a catted downpipe just so to the untrained eye it would appear as though I have an actual cat. And with the defouler my ECU says it's working. In hindsight I should have just save some money and went catless. And also for your other question. my 2 and 1/2 inch catback with the stock downpipe was completely droneless on the highway. Now the aftermarket downpipe there is definitely drone even at light throttle. I'm hoping some sound deadening in the floor of the hatch will get rid of some of it in the cabin.