There are some capacitive loads in the car, an arc on connection is normal. The question is, what is the standby current?

I would encourage you to measure the current by doing this:

Close doors, close trunk.
Verify all lighrts are off.
Using a DMM, connect battery to positive cable thru the DMM set to 10amp scale.
Wait three minutes.

At the three minute mark, what is the current value? .055 amp or less is spec. If it does not exceed that, you are good. BUT WAIT THE FULL THREE MINUTES, any reading you get in less time is inaccuratly high, you must give the modules all time to hibernate before evaluating current.