Hello, I have the same car as yours, so I will try and help. The breather box is located under your intake manifold. Connected to the top of the breather box is a short hose. This short hose is connected to a y plastic fitting. Inside this fitting is the flame trap. The flame trap is just a white plastic disk with small holes in it. Also connected to this fitting is the small hose that goes to the brass nipple under your intake manifold. It is a good idea to replace this smaller hose because it can become clogged very easy. In addition, removing and cleaning the brass nipple is a good idea. Furthermore, depending on how dirty your flame trap is, you might want to replace or clean out your breather box. Simple green works very well to clean it out. The 16v breather box is different from the none 16 valve breather box. For example, the breather box on the 16 valves has the hose leading to the oil pan as part of the box. In contrast, the non 16 valves has this hose seperate. As a result, it is a PITA to replace the breather box on the 16 valve with the intake manifold on. This hose is part of the box and it is more then 8 inches long. I have been told that you can remove it with the manifold on if you remove the bolt holding the transmission filler tube and move it aside. Here are the links to some pictures that might help.
http://www.volvoadventures.com/flametrapschematic.jpg
http://www.rprusa.com/images/fl_early.gif