I use the Vortex95 now, but I've tried all the unleaded in my area, filling it from near empty for at least two tanks worth of riding and I can't really pick the difference in how the bike runs - maybe slightly.
I use the higher octane since people say its better for the engine and runs cleaner...

yep fuel consumption will be high in the early days, it will get better the more ya ride it, so get on ya bike & ride girl  take ya time & do the same ride over different days, ride it a bit harder on the first day, then just poke along on the next run & you will see the differance, when I tried it over about a 180 K route, it use almost 2 ltrs more when I flogged it.

Hey SuziQ, yeah, the guys/girls on here know their sh!t.

I was getting very ordinary fuel consumption on my nightster. A month or so in and it is getting slightly better and better with economy. I'll report back once I have my first service, but I'm getting around 150km's on a 12.5lt tank when the light comes on and that's a mix of highway/city riding.

i get about 160k before the light comes on around 110khp

Previously I've had the light coming on at around 145km but the last two tanks have been unbelievably good. Filled at 185kms and the light still hadn't come on. I actually thought it was busted but the tank only took 7.6 litres so the warning light wan't quite due to come on anyway. What's changed:

1. Loosened up at last now it has 2,000ks on the clock

2. Using 98 octane

3. Since I saw someone on the forum say they fitted a tacho and found out they had been under-revving  I've been gunning it big time and changing gears much higher up the rev scale.

At this rate, depending on how much it will suck out towards the end,  I should be getting as much as 270kms from a tank which I think is outstanding. Not that I'd risk going past 200 before filling.

Note: The Iron is lighter than an 883L or custom.