Here are a few pictures of my 28% Extra 300s with BGX. Note, I installed the baffles after first flying the model due to overheating. The air hole below the stock opening was present since before the very first flight. The last picture shows the main air exit. it's about 3.5" X 5" long. There is more space between the bottom of the cowl and the bottom of the engine box than appears. Also note the over head shot with the lower half of the cowl installed and how much space has effectively been eliminated by the baffles to prevent air stagnation behind the engine.

John

Head on without the cowl.
3/4 above without cowl
Side view without cowl
[IMG]http://jndneff.home.texas.net/rcplanes/DSCN0050.JPG
[/IMG] Over head with lower cowl installed
Head on with lower cowl installed
Underside of lower cowl with air exit