Mate,
Brown Davis makes long range tanks (155L). Read more about it in this fuel consumption desert P38 V8 thread.
As I noted, I think they do hang fairly low or that might be an optical illusion. As I also mentioned in the other thread; since the spare no longer fits and the spare wheel well is not accessible due to the drawer system I am planning on fitting a custom tank in that space when budget allows. Judging by the size of the wheel well I figure it can fit an extra 120L of fuel.
Cheers,
-P

