Economy long trip, AU wagon, & mods

Tested newly aquired AU falcon wagon on long trip did 632km on a tank. DTE reading 8km on return. Filled up with 60.99 litres all the way till full same as before I left. I am very pleased with the result. Car was full with three kids in back two up front and the back of wagon full. Cruising between 90 and 110 kph with some hills and slow winding roads thrown in..
Works out to be less than 10 litres per 100 km better than magazine tests say it will do under ideal conditions. This was stock standard apart from a small section of the grill I cut away to allow more air to flow to the snorkel.
Im so pleased with the result on return that redback exhaust from cat to back fitted with mandrel bent pipe and two straight through mufflers. Total cost fittet $340 (magna was $200 just for one redback muffler so is much better value this way) (ITG filter for magna was $160).
Also fitted a Tickford snorkel which appears to be at least three times bigger a front than stock one (there is a much bigger one than the Tickford but cost $350 approx).
Also have a 3 inch pipe to replace pipe from box exit to first turn as it reduces too much at box. (a tip from off this forum)
Latter Im leaning toward a 1604 Wade cam as I seem to remmeber hearing somewhere than this cam can give 10% better economy and %10 percent more power (has unuasual specs with ex duration less than intake duration). Apparently works well from what Ive heard. Does anyone have this one installed?