Alright CPT G says save your deployment money or put it into paying the car off
Seriously, I would go auto-x first stock just to get a feel of how you and the car perform. Auto-X is usually more forgiving then open tracks too...trust me you don't want to lose it on a turn and smack a guard rail/stack of tires.
....but its your ride and at least you are thinking in the right direction for safety.
A set of wheels & tires will give you some more traction and if lighter free up some weight. My biggest gripe during a season of Auto-x was that if I got on the throttle too early with the VDC off I could easily spin the rears on the sport tires/wheels. I'm not sure if that's even possible anymore with the RE-11 305s in the rear.
Maybe you want to look into a rear diff since you don't have the Sport?