I have a SS backbox and a magnex decat centre.

recently a noise has developed, which is a constant high-pitched ring, audible only when the car is moving and the windows are down.

It is very, very, very annoying and I can't enjoy the hot days with the windows down.

Where on earth is this noise coming from? I can only assume it is something to do with the exhaust (which was fitted ages ago and the noise started last week).

Please help!!

 

May have sprung a leak, gaskets can break down and air escaping,

Could be turbo whine, which may be normal though may indicate worn core, or seals are on their way out.

Could just be noise from air around the car

More likely to be a gasket, with a torcj=h check around the joints for black soot, if there is soot on any of the joints this would indicate where the leak is coming from.....

 

I've had a few leaky zorsts and whatever you heard before the leak is usually what you hear after the leak, just 3 or 4 times louder!

 

Would it be a gasket if the noise is only made when the car moves?

Certainly not the turbo as I can hear that distinctively!

 

Leaky gaskets sound have been described as a continued wet high velocity fart, blowing on a reed and a zerbert (if you followed the Cosby show, you'd know...)