I do know this for a fact but I have heard it is slightly smaller than the standard Aero turbo. Also the lines are different so you would have to get now lines at least. The exhaust bolt pattern on the newer cars appears to be different but I am not positive.
to my knowlagde the viggen turbo is not a good as the 9000 aero turbo so it is a little pointless unless you have one and want to replace the T25 with it as to whether it would fit there are some fitment issues you would have to deal with like the suction pipe from the filter has a flange that bolts to the turbo on the 9-3 instead of the hose fitment the 9000 has
The aero should be a direct bolt in. According to the EPC though the oil, oil drain tube, and coolant lines are different. So you would need to soure one. IF you decide to go Aero route PM me. I have a brand new one hanging around.