Hi all, I was wondering if fitting a down pipe without a cat would help with my MPG? I have a 1994 ES 2.5tdi

Hi there fellow Land Rover fans. This is my 3rd Discovery and all 3 of them are throwing new tricks at me. This one is a 1997 300tdi ES Auto. Two days ago the whole car was vibrating on the way home from my Mum's and has dont it since. Its faily gentle but noticable when idling down the road but...