Split polygon tool (3)

I haven't used maya for a while and I've forgotten how to use it well. Anyway, I'm modelling a gun at the mo (a FAMAS), and I'm sure there is a way to mirror the edges you create with the split polygon tool (so when you create an edge on one side, maya automatically creates one on the other side of the model in the exact same place).

Cheers for the help.

Well create the modell in two pieces the other beinga mirrored intace then whan finished combine the two. Amya will now mirror all operatios!