I think you could be looking in the wrong area. U2105 is an engine fault code, which perhaps helps explain why it comes on under heavy acceleration or travelling uphill. I would have a diagnostic check done on the car to see if you can better home in on the cause of the problem.

I don't expect the prices to change much in the next 5-10 years, but in the longer term I think the HSV GTO will become a much sought after car. Look after it and keep the kays down as much as you can.

I have no doubt that it was frightening and I'm equally as sure that the experts you have spoken to are correct, and that the explanation you have been given is pure fantasy. It would have to be a major side impact to trigger the bags and it would seem that just hasn't happened. Something being flicked up from the road is not going to set the bags off. Go back to Holden and demand a proper explanation.