occasionally get drumming vibration sound when accelarating

I have noticed that when applying the accelarator i occasionally get a drumming/vibration sound coming from the car.

I had this a year ago on a BMW 540. When applying the accelarator i got a drumming sound and the car would vibrate.. spent a fortune on diagnostics saying it was cylinders etc.. it turned out to be the CAT that had gone.

Im just wondering if it would possibly be the same on the land rover.

are cats expensive for the Land Rover Discovery (2000 xreg)