HI GUYS IVE GOT A DISCO 1995 2 LTR PETROL 16 VALVE OHC OLD ROVER ENGINE HAD IT A FEW DAYS ONLY I WAS TOLD BY PREVIOUS OWNER SHE DOSE 20 MPG ROAD TOWN IM ONLY GETTING 15 I CANT DRIVE HER ANY SLOWER OR ILL STOP THINKING OF FITTING A DESIEL ANY ONE NOW HOW HARD TO CHANGE AND WHAT PARTS WILL ALSO...