If I am not mistaken the factory Ford turbo'd Inline 6 has more hp than the 6.0L Holden V8. I read that a couple years ago in Automobile mag, dunno if it's changed. Ford seems to have a good grasp on Australia.
The turbo I6 has less power but it is certainly faster than the 6.2L Holden.
The F6 Typhoon leaves the HSV 6.2L V8 Clubsport R8 a car length behind in a straight line.
http://www.youtube.com/watch?v=6BOMapeA6DgSome guys street racing:
http://www.youtube.com/watch?v=h54MKkxX1qQThe XR6 turbo, with a small amount of relatively cost effective work will out-muscle the XR8 pretty easily, I believe.
The Australian Ford I6 engine is a great engine... I have a mid 90s I6 and it is the nicest 6 cylinder engine I've ever driven. The auto gearbox is a let down, first gear is massive in it... 70 kmph before it'll shift to 2nd, where it really starts putting power down but other than that, it's a great engine. Loads of torque... sounds great for a 6 and they're tough as nails.
I still think I'd prefer the XR8 over a the XR6T.... Quicker off the line... sounds better and the speeds at which the XR6T would start to pound you would get your licence suspended in short order.