My 1.6TDCi has developed a coarse rasping sort of noise when accelerating quite hard. If the car is accelerated gradually there is no rasp at all.

The rasp seem to kick in when torque is quite high, so could it be related to the turbo perhaps? There seems to be a lack of performance too. It doesnt seem to take off as well as it used to during relatively harder acceleration.

I've been told that there is possibly a split in an intercooler pipe. Is this reasonable to suppose?

Any other suggestions would be appreciated.