Hi its definitely the rubber section that joins the duct to the turbo, I used to get this a lot on the two Mondeo cabs I ran and after getting Pixxed off with keep paying £150 for a new inlet trunking just to get the rubber boot I finally measured the old ones I.D. Both ends I finally bought a stepped section of silicon hose that was within 2mm of the right size both ends I.E. one end was 52mm the other was was 48mm these are called reduction pieces and are available from ASH Silicone hoses on line and for about £16, that put it to bed for the next 150,000 miles until I sold the car, you might even be able to buy the boot as a repair section on eBay.
Steve.