Thanks for the comments guys.
Ales & Energon, it is the kit with the engine - I originally intended it as a quick build without the engine but I had a rumage around in the spares box last night and came up with these:
I think the carbs are from Replicas & Minatures - not sure where the "trumpets" came from. Obviously the builder got some cash for his birthday and spent it on the engine!
Cheers
Andy