Exploded view part trials aren't really useful for production drawings. Here are a few things that would greatly improve the utility of the part trails.

--Make them invisible or hidden where they pass "behind" other parts.
--Allow for more than one part trail per part with user-controlled location. For example, this would allow for showing part trails between several holes that align between separate exploded parts.
--Allow for control over line style, weight, etc. like other entities.