i have a 1.6tdi with 36,000 miles on it and ive not had any problems with my car i give it a run upo motorway baout 95% of time time.my work trek is all motorway with about 5 minutes a roads... and i give it abit of welly once in a whule to help clear out the dpf....i have no backbox now so i can notice alot more when the dpf is cleaning because i hear a loud drooning sound coming from the back of my car..sounds nice and burbly on idle though