So i built a long range tank from alloy ( approx 85lt ) , since the standard tank had a fuel smell i couldn't track down ( changed all fuel lines/breathers ETC ) , so i decided to cut the stock metal tank up and make it into a long range tank as well. Roughly 26cm longer , which equates to, again, roughly 28 litres. I took some photos of the insides, so you can see exactly what is in them, and what can "fail" . Pics are in no specified order. What i found when slicing the tank was its got 2 breather pods, these are connected by a short rubber hose. This hose has disintegrated, So it was replaced with a new piece ( approx 4cm long, circled in pink) and the main length i joined with a piece approx 20cm long , and welded a support to the top side of the tank. Also found my fuel smell , the main breather/fuel return pipe had cracked its solder to the tank on the inside , i have put a support in to minimise the expansion/contraction that would have made the solder break in the first place and resoldered the pipe to the top of the tank. I also fixed both pipes externally as they were cracked and missing solder ( see attached pic ). Tonight i have just finished welding the extension pieces onto the tank. TIG welded one side and mig welded the other. I'll pressure test it and see which one has sealed the best. Im guessing i'll have the odd pin hole as it was stitch welded to minimise heat distortion.