Mate of mine has an Aprilia RS
............... 485cc with 100rwhp 50ft/lbs @9,500rpm.
With 39mm Mikuni's it drinks from a fire hydrant.
Stock tank holds 16.5 liters just like a GRiSO, except he has got an ETI kevlar fuel cell.
Exact same physical external shape, dimensions, appearance, mountings etc.
Due to its thin walls it now holds 22.5 liters, Oh and empty it is more than 2kg lighter, although fully fueled that will be more than negated.
Just saying ............... people have wished for more tank capacity.
With a smaller battery cavity in the back of the tank (lithium battery) capacity could be increased again.[You must be registered and logged in to see this link.]