The Clarke tank comes with its own fittings, such as tap, cap and the long mounting bolt that goes through the frame at the front of the tank (although it has an imperial thread). The MXM graffics are holding on very well , but I haven't put fuel in the tank yet . I think that the secret with the MXM graffics is to fit them as soon as you get them , when the adhesive is strong and fresh. You only get one go at putting them on straight though, as the glue is really strong and you would probably destroy the decal trying to get it off or move it . I had some older MXM graffics that I had stored for a while, that the adhesive had seemed to lose strength over time and they wanted to peel off once I had got around to fitting them to a tank.
Fortunately the 500AE has aluminium engine cases , instead of the magnesium used in the CR/WR/XC motors, so I don't have any issues with corrosion . In my opinion, magnesium is a curse because of corrosion issues and the difficulty of welding repairs and is not worth the trouble for the insignificant weight saving .