if you want piston slap, rattles, oil consumption and spun bearings, buy a LS1.....
my 5L has no probs keeping up with HSV VY/VZ/VE's on the circuit - even down the straights. Most of those HSV's have more power than my 5L on paper, yet don't seem to pull away down the straights, even with lower diff gears. They only seem to start winding up by the end of the straight, whereas the 5L punches harder out of corners and reaches it's potential earlier. I suspect on a long straight like Bathurst they would have the legs, but I was actually quite surprised that my 5L could keep with them at the 2 different race tracks I've driven - keeping in mind we're reaching around 200kph at the end of the straights. And my 5L is nothing radical. Just goes to show manufacturers quoted power figures and dyno readings don't mean much in the real world.
I'm not suggesting LS1's haven't got more potential than the Aussie 5L, but the 5L has more than enough potential to keep up with the LS1's, without spending a fortune.