The metaphor of bolting on a turbocharger tells us almost nothing except that the Flipper's architecture hasn't been completely discarded. It does not mean that there have been no modifications at all. The metaphor is clearly just to illustrate that the current chipset used the old one as a base rather than starting from scratch. How hard is that to understand?
People try to read way, way, way too much into metaphors. Like when Mark Rein said "It's no Intel integrated graphics," people really went to town trying to decide which chipset he was talking about and what architecturally was specifically better...when any rational person knows he was just saying "It's no steaming pile of crap, but it's certainly not cutting-edge, either."
Stop trying to read detailed technical statements into or out of metaphors and marketing speak.
IMO, the latest intel integrated graphics could put out better graphics than the Wii has so far, so if epic says that the wii is noticably better than intel integrated graphics and it's not just a bs pr comment, that at least means the wii is more than an overclocked cube. The newest intel integrated graphics has decent speed, dx9 shaders, and better IQ than what the wii has shown.