[STROKD]

bigger wing in back
splitter in front
check allignment, throw a touch more toe-in and decrease caster. this will cause the car to be much more stable and less twitchy. Dont get crazy with the toe, 1/8" total is all you need, maybe 1/8" on each side which would be a LOT if your car has problems tracking straight.

wing in back will help the most though. esp if you dont have a spoiler and have a flat trunk lid. dont need a stupid indy car wing, just a functional spoiler, and the factory ones usually suck ass. look at Roush or Saleen for alternatives.