Fitting the Filler:

There are several options here, depending on the car and whether you have a Tow Bar.

We'll start with a picture of the LPG filler box.



The actual filler connection needs to be attached with the supplied machine screws and plate (seen from both sides). Note that the Lugs on the filler should be horizontal to comply with COP 11





If fitting in the bumper you'll need to remove it by following this guide after marking where you are going to mount the filler. Remember that the box is quite deep and you then need to leave enough space for the pipework too 

Cut a 70mm hole in the bumper/panel (there is a special "clamp" style cutter for metal panels)...



... and remove anything on the inside of that hole which will prevent the box sitting flat



You'll also need to cut out the notches which secure the filler box from rotation, a flat file works well here (even in a metal body panel)



Use a thin bead of sealant around the lip of the outer part of the filler box. Ideally something like Silkaflex, but black RTV/cam cover sealant will do. The inside has a rubber O Ring which seals it.



Then put the 2 parts of the box together with the panel/bumper in the middle. It then screws together with the supplied self tappers.



The fitted filler looks like this on the bumper...



...or this on a panel





Inside the car, the fillers fitted in the rear quarter panel look like this





Be aware that if you want to fit it centrally (like the upper of these two pictures) that the Fuel Flap Locking Solenoid needs to be re-located fractionally.

IMO, fitting the filler to the rear quarter panel is much more "risky" as you only get one chance to get it right  It's also better suited to 4 hole tanks than single as the vent hose would make it very bulky inside the cubby hole.

There is also the option of fitting the filler behind the number plate on a saloon, which a couple of people have used, but I don't have any pictures of this. I believe it also requires a little bit of welding. Perhaps one of the people who have done this can add some information and pictures.

By far the easiest solution is to mount the filler on the tow bar, although you'll need a "shin breaker" for this 



If the filler has been fitted in the bumper you will need to attach and tighten the fill pipe before re-fitting the bumper otherwise it will be a little tight tightening the nuts between the bumper and the fuel tank