Very variable as to when the fuel light starts doing its thing, often goes on and off alot, but average mileage 55 - 60mpg depending what I've been doing. Thats with MTC after market cans, K&N Stage 1 and CO2 cranked up 10 or 15 can't quite remember. Found the filler a little odd first time but no problems since, just nice and careful once its getting to the level of the inner bit (sorry for the highly technical term there folks).
Cheers,
Selina