diffrent oil sump?

[ricola]

If you look right in the middle of the manifold you can see a rigid pipe with banjo fitting on the top, just to the right of the 3 small black pressure pipes, you can just make out the grey connector to the injector to its left.

A fifth injector upstream is a cheap/simple way of upping the fuel requirements. They are commonly used in aftermarket upgrades if the standard injectors can't cope with the upgraded power output. As there is only one injector the amount of fuel in suspension is relatively small in the manifold. If adding aftermarket turbo/superchargers you can also use the fifth injector with an aftermarket ECU to add in the extra fuel and leave the stock ECU alone.