You guys say you have a dirt car like you have a car made of dirt :lol:.
I would suggest the right tires or you'll be spiining and sliding all over the place.
One thing you can do is strip weight. Ac components, power steering, rear seats, spare tire and Jack, rear plastics, front passenger air bag, passenger seat, etc.
Theres a lot you can strip haha.
Otherwise intake/header/exhaust are the most common "performance" mods. However you won't get much from it at all, itll just feel like it cause it sounds fast lol.
The only other things to do are build the motor or boost it.