11 hours? It is a bit of work to get the sub-frame mounted, but if a experienced installer started at 8am and was not done by noon then he was messing around or ran into an issue. I would have the dealer do it though, unless you have experience in such things. Sometimes a hole needs to be reamed a little, or bolt is the wrong length that came in the kit, or a fitting is wrong. That doesn't happen often, but often enough to create an issue. We have a hardware store of bolts, fittings, etc., so we aren't set back if we run into little snags like that.