Damed if I know You have me. That info came from the ford web site. I have read it some where else as well. Hang on I will go and look. You have the car and the instruction book so you must be right, but I would be asking the question. Just pulled out the Cat and it definately says VCT and XR8 have a 6 stacker in dash. Can't believe they would give you the wrong unit but something ain't right
With the xr8 there is only two models. Prestige or premium which is an extra cost. Either way the model you have should be a six stacker in dash. In fact I can't find the boot mounted stacker listed anywhere on the spec sheet. Looking at the unit the slot does look bigger then my single disc unit.
In short your unit should definately be a six stacker in dash and if you think it is not, the wrong unit has been fitted. I would hate for you to have a unit that does not have the features advertised as standard on series 2. The only other explaination is that you can feed one disc into the unit at a time and it stores it, but that is a guess and I wouldn't do it before checking the situation out and if I were you it is something I would be doing. Having said that it may make no difference to your planned stereo swap anyway!