Australia's vehicle emission regulations require new vehicles entering the Australian market to comply with emissions controls and the current available technology to help meet these regulations includes the use of catalytic converters and Diesel Particulate Filters (DPF).
When a vehicle is certified for emissions and fuel consumption the engine calibration is tuned a certain way to meet these regulations. If the DPF is tampered with or removed, then the engine will not perform as the manufacturer intended. It is therefore essential that these devices continue to remain functional and on the vehicle. For this reason, there is no legislated exemption available to remove these components.
In circumstances where a particular make or model of vehicle has shown to be a fire safety risk, the Australian Competition and Consumer Commission (ACCC) is responsible for initiating and executing a safety recall. ACCC has taken this step for certain vehicles due to the build-up of grass in the cross members and underbody components near the DPF and exhaust.
Vehicle manufacturers recommend regular inspection of the underside for this build-up matter and that the whole exhaust system is a hot area once a vehicle is running, so regular check-ups should also be performed around the remaining exhaust area.
For Toyota DPF off road /rural use go to here.
For Ford diesel engine information go to here.