Changed the rocker cover last night on the S1 from cork to the rubber one, changed rocker and charge pipe also.

Drove today to see if the rubber one let oil out and it all seems ok.

BUT...my inlet manifold seems to be hissing quite loud.
Can here it sat in the car, what does it mean? or is it supposed to do that?

 

if it hasnt done it before Id guess you have a vac leak. Check all the pipes mate and see if any are leaking.

 

Yes definatly sounds like an air leak to me.

 

check the pipe under the throttle body may of been disturbed