Once you have selected all 3 options, the image will change to your selection. In all images the loco cab would be top left, and front of the bonnet bottom right.
Below is some more information about the options available.
There are 2 styles to choose from: Curved and Straight. Both can be seen in the image gallery.
Exhaust Exit Angle
Imagine you’re stood in the cab of your loco. Which side does the exhaust exit the bonnet from? Top, Left or Right.
Top off your exhaust or just go with the simple pipe. To determine the angle, again imagine you’re stood in the loco cab.