I don't think it's so much that they aren't large enough. I think it's that they didn't put anything on them. Or they loctited them in. I laughed when the directions said to use loctite on the bolts into the egr valve, then I smeared them up with anti-seize and screwed them in,
The shop manual states to apply loc-tite only to the bracket bolt that goes into the egr cooler.
This is extremely important and must be done to prevent the bracket from coming loose, allowing the egr supply pipe to wiggle around and break, and then set fire to the surrounding plastic bits.