Right, a bit more research has thrown a few more details up. In April this year this car was running 11.6@122 mph on stree tyres, a GT3071R turbo, race fuel and developed over 500WHP ( so around 560bhp) and at that level will have internals. The GT3071 is rated at 560bhp, so that matches up with Garrett's own outputs. Now, 122-123mph terminals are still a reflection of power over the distance and even with slicks added to gain another 10mph on terminals over the same distance needs another 200+bhp in a FWD motor at 1300+kg.
Some great power, but I've still to be convinced!