If I were you and I could do things differently for myself. Keep the R/T or get a beater. Save up as much money as you can. Find a good deal on a car, get a loan so payments aren’t rediculous and use some of the money you saved to mod this car. Drive it and get a feel for it the first summer you have and then mod her up the next summer.
That is what I would do differently if I go back in time to when I was 17. Thats just my .02 from my personal experience. But we are different people, you make a better you and I make a better me. Good Luck with your findings.