What you should be seeing is the same voltage as at the battery positive terminal, with no more than a .1-.2v loss.
Seeing 11v, without knowing what the battery is at tells us very little.
If you have a drop greater than recommended then odds are you have dirty connections (bulkhead, ignition switch connector, ballast connector, etc) or the ignition switch has dirty internal contacts. Don't forget the negative connections as well.
If your battery is low, charge it up.
I might say .5V worst case due to all the flipping connections, age of the harness etc. Also be aware that the same V is what the regulator uses to determine the charging rate. An excessive V drop will likely lead to overcharging as well . Do not overlook your battery connections and grounds
keep us posted.
