First I'll say do whatever you want with your money. It is, after all, yours.
Secondly, one great way to have more money in your current position is to not spend it on your truck. I'll be one of the buzz killers and say concentrate on your school and job right now. Do well at those with a good vision of where you are going and the truck parts can come later.
Putting money in modifying a vehicle is just like putting that amount of money in your driveway, soaking it with gas, and throwing a lit road flare in the pile. It is fun, you just have to decide if it's really worth it right now.