Just got back from my holidays & completed my milage calculations.
I towed a 25' trailer, 3 weeks of food, 40 gals fresh water, 5 20 litre bottles of water, 300 lbs firewood, 3 bikes, 3 kyaks, bbq., 3 people, 1 cat. To say the least I was loaded.
12.5 miles/gal or 22.75 L/km best tank. Average for 2403 km trip was 11.8/26.
I've only done the timing without TBS. This is a 1.5 mile/gal improvement.
The flat spot through 2500 3000 rpm is now gone & has useable power from 2500 to 3500 rpm, that in itself is a 500 rpm improvement.
This was/is one modification worth doing.
P.S The milage improvement has been seen with my daily city drive to the tune of 16miles/gal 18L/km.