Hi All,

Car - '54' Blob Widetrack STI (6 speed)
Oil in gearbox looks clean and at the correct level.

The car makes a faint whistle that is only noticable at 30mph or higher, this only happens when the gear selector is over to the right (in 5th and 6th or in neutral between 5th and 6th) it happens in gear or out of gear, it happens whether the clutch is pressed or not.
The whistle increases in volume as road speed increases but does not increase with rpm (tried increasing rpm with clutch depressed or with the selector to the right between 5th and 6th and if road speed stays constant, so does the whistle)
If the gear selector is pushed towards the left (i.e. 1st and 2nd) the whistle disappears.
Anyone have any idea what this could be?

Thanks,
Ryan