Ph1 172 throttle body

[essexdon]

Hi people, just bought a ph1 172. It has a cheap cone filter fitted to it and am looking at getting a standard air box fitted soon. But there seems to be a hole on the body that seems to missing a pipe to something else. I am just wondering if anyone could point out what this is for or if it will make much difference if its open or closed off. Here are some pics of the hole. Cheers

 

[clio ph1 Belgium]

pipe from the main brake cilinder