Do you actually need this ?? In 4 Scoobs never touched it , looked at mine and it snapped off in my hand 

The coolant overflow? Yes. If you remove it when the engine cools down it will suckling up air instead of coolant 

Ah cool ! I need a new pipe quick then the base of the overflow section behind the passenger headlight snapped at the junction to the pipe 

When I broke mine I just wedged a bottle in between the intercooler pipping and the light. Then just pit a rubber hose in there and worked a treat for a good 5k miles

Cool !