[Razorback1980]

Everyone has their own way of doing things but I always coat mine before assembly making sure I fill every crack or void in the connection and here is why. If you put the connection together first, there are air holes between the bolt and the connector whether it's just between the stud and the connector or between the two connectors. The whole purpose of dielectric grease is to remove the oxygen and other contaminants that cause copper to oxidize causing a poor connection. If you trap those elements in by applying after assembly you have indeed removed any more from going into the connection but you have also caused those already inside to not be able to escape and corrode your connection. The flow properties of dielectric grease allow it to be squeezed out of the way to provide the electrical connection but fill any gaps preventing corrosion from inside as well as outside. Here is an article on RX7 grounds that explains it very well...not Porsche but principles are the same. It's kind of long but it has a lot of good information in there. I do my battery cables the same way...coat the terminals then attach cable end. Same principle.

http://www.aaroncake.net/rx-7/grounding.htm