AussieSpeed alloy rocker covers for the Holden Gemini 4 cylinder Isuzu engine are vailable in panel tops and finned versions like the one shown above.  These Gemini / Isuzu valve covers are 25mm taller than stock to allow for higher lift cams and modified valve train and they look real cool.  They are made from sand cast aluminium [Aluminum for our USA friends], they are thick, rigid and polish up to a deep lusture becasue they are sand cast an not diecast.

 

Each rocker cover comes with nut extensions that you screw onto the studs that hold the standard cover on, the photo below shows you these studs, and then you put the tappet cover in place and bolt it on with the screws supplied. Click in the image to see a larger photo.