Thanks Jeff,
I did try getting the smell of Diesel once. Lets just say it did not work and made a bit of a mess. I have seen snoke units fitted to 7mm diesels and it is quite good but as you say not at all convincing.
No worries on the sound chips, I might even have another one when I see you next as I am thinking of getting my class 31 reblown.
Cheers Peter.