Well not quite, the limited edition GT4 had the 300 engine, you'll find these on 04 or 54 plates. You may also find some of the pre 06 cars have had an engine remap at Abbey or RS, doesn't quite take the engine to 300 though, more like 285/290 I think.
EDIT, probably worth pointing out that the facelift 2006 300 version gained quite a bit of weight, about 85kgs, most likely some undocumented beefing up underneath the skin, so overall performance not much different to older versions.
Pete
GT4's were 05/55 plates