If it was me and my money I wouldn't bother with liquid yellow on the Twingo.
Liquid yellow is a lovely colour but to me it doesn't suit smaller vehicles. It looks amazing on the R26 where you have big panels that show off the colour, the Twingos are full of angles and it breaks up the lovely colour. It's the same reason that the Clio 182 in Inferno never really looked as good as a Megane 225 in Inferno.
Also, it puts a massive amount on top of the price of the car for a colour. Yeah it's nice, it would be rare but no RenaultSporth olds it's value that well no matter how rare.
Personally I think Glacier White is probably the colour that best suits the cars shape and styling. It highlights the arches and bits that define it as the RS.