Here is a graph for you to compare. http://www.profixauto.com.au/xr6_ute.htm
I don't know that a gut feel that your engine is down on power is a good reason to go to get a dyno run. They all vary and you have to take them as tuning tool before and after stuff to get value from them.
1/4 mile times are usually a good indicator of power particularly terminal speed.
What were your times and what were you expecting? An AU XR6 VCT should do high 15 to low 16 sec 1/4. Remember the VCT sedan is 150kg heavier than an AU sedan because of the independent rear end. To make up for the extra weight the VCT would need to put out abou 178fwkw to match an AU X66HP.