Now the next step is locating which cylinder if you plan on fixing it yourself (with engine in car). Pull the spark plugs and I pretty much guarantee you that one will look different. Mine was rusty. I don't know your plans, but with an n/a especially it isn't insanely bad to change the head gasket w/engine in car. I did it on my TT. It was my #5 cylinder which is quite common apparantly.