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.