I guess Volvo can choose to have a T5 on 5 Cylinder cars only, and etc., but why not have T5 on ALL five Cylinder turbos? The lesser turbo versions on each car are not even listed by Volvo. They are probably all T1 through T2 or not even. Some turbos even start with "k" for example, and are usually not listed. It is just a coincidence that Volvo does this. The turbo itself, not the car, is called a T5 turbo. True, Volvo 5 cylinder engines may have T5 turbos, etc., but it does not mean that a T5 is a turbo that goes only on 5 Cylinder cars. For example, some one who works with me has an Eclipse turbo with a T3 turbo. And that T3 is an upgrade to the stock turbo he had before-no idea what kind it even was. And the engine is 4 cylinders. Hope this clears stuff up.
Anthony.