I'd say around 15.7 Auto
15.2 Manual
Thats only from what I've seen but it's generally the times that are ran. Depends on the motor that it's all bolted to also. Manual VN V6's are usually 1/2 a second quicker.
With the higher diff gears you might pull a 15.2 in the auto. V6 Vengeance from street commodores couldn't even get a 14 with a cam, haltech, extractors, exhaust So again it depends on the auto, shift kitted or not they still don't get the power to the ground that the manuals do.
Theres one way to find out, go and run it
Jake