I'm thinking here of the class 150 DMU, which is currently available with sound in ATW livery, however the upcoming release of the GWR version will not be available sound fitted. Ignoring for the moment the merits/drawbacks of manufacturers sound models, is in this instance Bachmann missing an opportunity to upsell? The 158s and the 66s are both offered with & without sound, so I'm puzzled, especially as the company already has the soundfiles. I've used Bachmann as an example but I'm sure this could apply to other manufacturers too.