Well just done a test with fuel additive. The one Mark Dale uses mine runs 40″ tyres and 5.1 diffs so economy if far from good far far from but I would never change a thing i Made it I love it !!! So put some in as stated on new application. Well I was suprised stright away more power quicker acceleration Loved that It was ok but now more responsive. Well worth it I done 200 mile round trip in it to a show and was getting 15 to gallion but now 17 to 19 well happy x2. Now more power more mpg well worth a try !!! Thank mark dale !!!