Malta

I'm not sure I understand your question. You are always at liberty to travel on your own before and/or after a tour, and I think it's a good idea to do so.

If you are referring to a Rick Steves tour, he does not offer any extensions. However, you can always do these on your own. As part of your tour, you get a discount on trip planning services from his office, so you can use this to help you plan a trip to Malta.

You can easily do Malta on your own...they even speak English (and Maltese) there. It's a short, inexpensive 40 min flight to Valletta from Catania via Malta Air. I went to Malta in combination with Sicily on an independent trip - I definitely recommend a side trip to Malta but I would try to extend your trip to at least 5 days or more. Even though Malta is small, it is jam packed with interesting sites, many of which are in Valletta but some which are spread out throughout the island. Taking a ferry to Gozo is also a treat. If I had to doit over again, I would have stayed at least one full week in Malta, if not a little more (to see Malta AND Gozo properly). Malta is super easy to get around using their bus system. Get the Bradt Malta guide - it's an excellent guidebook for Malta.