weird engine noise from my s3

[gaz24s3]

Hi everyone, had this strange noise coming from engine bay on my s3.. sounds like some where under the engine cover!! it happens when i accelerate hard to 70 ish then stays on until i slow down to 25ish.. im running a revo stage 2+ map at the moment but theredoesn't seem to be any power loss!!

thanks for any help
Gaz


audi s3 whistling engine noise?? - YouTube