you could also just get a sheet of Polystyrene and epoxy/rivet it in place then cut a hole with a dremel to fit a new snorkel in. Polystyrene can be had at any hobbie shop for cheap, like $2.00 or less
Might be cheeper than replacing the whole unit.
The DukeII airbox sounds good but pricy considering getting a new battery, box and filter.
Anyone got pictures of the battery relocation?