strange exhaust noise - anoyone had it before ?

[darko]

my exhaust is making a howling noise when i reach the higher revs - it happened a couple of times late last year but now it is happening all the time. anyone else had something similar ? the noise comes from the back of the car and is a high pitched howl

 

[mazzy]

Is that a good thing??

 

[darko]

not a nice howling noise ! it sounds like a restriction, perhaps the baffle has collapsed inside ? it only happens at higher revs and particularly under load (i guess thats when the exhaust pressure is greatest) i was worried it was the haldex before but I have now found it happens just reving the engine at stand still.