Well, if you get in a position where someone is closing on your 6, but not closing fast enough to easily force an overshoot, you have a few options. These are all dependant on your height and speed.
1. If you really want to play it safe, go full throttle and do a split S. If they follow you down you can roll into a different direction when you get close to pulling out.
2. If you want to be sort of tricky, CUT throttle and do a split S. The enemy will assume you are going balls to the wall, and will jam his throttle forward to pursue. If you can manage to avoid the shot that he WILL get before he passes you, then you have your overshoot.
3. A hard flat turn is also a good defensive manuever- but you have to time it right. To late and you'll be dead, to early and they'll follow you into it. If they follow you into the turn, wait until their nose is almost pointed at you, then reverse the turn. You shouldn't do a flat reversal- you want to either be climbing or diving a little bit, and using your rudder to get out of plane.
OK, i gotta go. I'll post more in a few days when I get home.