for rally cross, you aren't gonna need a skid plate, a stage rally car yes, for suspension, and the money, you have 2 options. the first, and not very good, you have a ksport damper/spring. about 900, they provide 4 way dampening, and swappable springs for different rates. there are several opinions, but most go w/ about a 250 front and 225 or 250 rear ish, it depends on your setup and what you like. the next options is hotbits. they run about 1700, but they are some of the best out there. they are 2 way dampered. and they run an external resevoir. plus rebuilds are cheap. you can go w/ DMS, or ohlins, but u'll put more into your suspension than ur car is worth. your brakes need to updated next. you have better control w/ the svt brakes in the rear. the handbrake is easier to work w/. then TIRES TIRES TIRES. and lose the sways. you'll have a highly competitive setup. after that, its all about learning your car. (ie, turning the car w/ the brakes, not the steering wheel!)
Now I rive 2 7.3 L diesel trucks!