The XR6 Turbo and XR8 in the BA/BF series are fairly close "stock" but the XR6 Turbo does have the slight advantage being lighter. Once you start modding them the XR8 gets BLOWN out of the water wouldn't keep up even if you supercharged it. as for the new series the FG XR6 turbo is leagues above the FG XR8 in stock form, theres talk that the XR8 may get phased out.

I'm not sure who you were refering to but I'm from Geelong, Victoria about 40 mins from Melbourne. I've noticed your from QLD which is where my SRT came from