Hello all my 2002 c5 2.2hdi failed emissions ive been told to put some good additive in the diesel and go and blast it,, my HDI has no particle filter in and no cat but as i understand it themot cant detect no cat or DPF in a diesel, i understand the new rules that it must look like the DPF is there mine is all hooked up with no insides and the ecu mapped for no DPF.. iv been told this stuff is good https://www.dipetane.com/motorists/nct/ the guy said put a litre to half a tank and blast it, has anyone else used this stuff

thanks
Andy