Yesterday was driving and went to pass someone.. Hit around 5 or 6k on the tach and heard a hissing sound. It seems to pull fine has lot's of power up there still, but that noise doesn't sound to healthy.
Curious if you guys had any clue where i should start looking? It just sounds like air.. Possably some liquid maybe?
My coolent is still full, oil level seems fine... Where should i start looking now?
This is an S5 N/A GXL model.

Thanks

 

Ok well today, two days later it seems like its gone.. And i havent done anything but check the hoses...? haha
Anyone care to explain?

 

could be just your air pump something around there leaking