Kev: The bonnet was done when all the kit was fitted, so i could say how much it'd cost individually. Its basically a metal plate welded onto the bumper, then cut and smoothed into shape.
Dave: Yeah, i think the pretensioner went off when we removed the original seats, but im not sure... thats the only time i can think of anyway. Not sure on the airbag situation, ive got a different steering wheel in there with no airbag.