Good question Moparlover and there are no doubt numerous reasons for this disparity. However, it can't be based on any lack of performance, particularly in the final FG X-based XR8 and XR6 Sprints released in 2016 (just before Ford's manufacturing closure) which are my favourite XR Falcons. The XR8 Sprint at around $60K was about half the price of HSV's GTS yet it squeezed 345kW/575Nm from its supercharged 5.0-litre V8 (with the overboost function it was more like 400kW/650Nm) and was just as quick from 0-100km/h (4.5 secs) as its more powerful HSV rival. The lower-priced XR6 Sprint with its hot turbo six had similar grunt and 0-100 times. If I was to buy an XR Falcon to keep as a classic, it would be one (or ideally both!) of these.