there are plus's and minus's, it's not as simple as gareth is saying.

if the radius of the bend is not that tight, the difference in wheel speeds is not that great.

what you can get with an open diff (or even a shit lsd like cossies have) is that the inside wheel doesn't have much weight on it because of body roll to the outside of the corner, so it loses grip and spins. with a welded diff that would not happen allowing you to power out of the bends quicker.

as said, many 'banger racers' or stock cars have welded diffs, and it's not just to make them look good is it? it obviously helps with traction to have both wheels driving all the time.

what can happen is that because you have such good grip at the back, when you power on, but not so aggressively as to initiate wheel spin and power oversteer (not a drift )the front can push wide in an oversteer situation.

if it's for track only, i would say do it. especially if diffs are cheap and you can swap them out easily. then try the difference and see which you prefer.