Phil has a point there,it does all depend on were the loom is because what he says about vibration is right.Iirc F1 stuff is crimped and soldered because of that reason.Solder can crack,as for using a megger I doubt most people know what one is never mind owning one.I think the ones I used to use at work chucked about 1000v down the line to check insulation breakdown.It was easier using machines that you just plugged the NEW looms in.If you want to go even better on wiring things into a block you cant go wrong with stycast.If it was good enough for the aerospace industry its good enough for a car