Billy,

Down-Elevator is the Master, Left-Rudder is the Slave, try 5%. I have had numerous models need some type of mix to get inverted flight "right". Basically, any time you are using down-elevator you will have the rudder coming in via the mix to counteract the thrust. The Abbra is the only plane I've had in a long time that doesn't need any mix in this regards. All my wide body-type planes needed something. If you need more than 7% of rudder mix, depending on the whole airplane, it may be better to fix it with like 3% rudder to down elevator, and some amount of aileron to down elevator - depends on how bad it is.

Try this after you do the stuff Troy suggests, like making sure the elevators are tracking, etc.
See you at the Tangerine,
Jim