I got one of these bags, called famsa, italy company and its well made if a bit wierd to use (straps and zips all seem to be backwards) but it all works ok. It expands a bit but depending on what bars youve got ie non standard means it might touch a bit on full lock.
http://www.windingroads.co.uk/shop/p...o_max_tank_bag
i got mine second hand from another forum member as i wasnt wanting to pay that price.