A locked front diff will give you a bit more on power steering, but will take away off power steering. Personally, I don't like the locked front diff. It makes other parts break, especially the CVDs. What I do is run the front diff noticably tighter than the rear diff. This will still give you more on power steering, and the front diff will still be able to slip in a wreck. That will keep parts from breaking.
If you are really interested in tuning your chassis for the best possible handling, you need to buy XXX Main Touring Car Chassis Setup Guide. It's US$20, and it is worth every penny. The knowledge gained from reading that book has taken my game to a new level. I gained more than 3 laps at every track I race at simply by reading that book and applying what I learned. It is the best money I have ever spent, and the knowledge applies to every touring car.
Here is a link to the book:
http://www.xxxmain.com/bookz.shtml