DISCLAIMER: OP is almost 19 and doesnt care for any sort of practicality I will take suggestions as well.
Oppo its time for you to choose, Turbo 4 or N/A V8. Lets put yourself in this situation you live in the bay area and currently have a ‘15 FoST with a new job so you’re stuck between extreme mods on the FoST or a modded ‘14 Mustang GT
The FoST mods:
Air Suspension with Accuair E-level
Splitter / Rocker Panels
Chassis Reinforcement (subframe connectors)
All LED Lights
Probably Brembo 4 Piston Brakes
Power should be in the 270whp and 370 wlbft range enough to DD
Advantages: to modding the FoST like this will be that I currently have 0% APR on this car and warranty work will be easy to get done with my dealer connections even with major mods. The FoST will be about $400 less a month if we include insurance costs. The FoST will also be much nicer place to sit in than the GT for a daily commute.
Disadvantages: are that the FoST will be much slower than the GT, not look as cool and probably get about the same mileage as the GT.
2014 Mustang GT Build:
Boss 302 Head
Air Suspension Accuair e-level
One Piece Driveshaft
GT500 Rear Valance
Corsa Sport GT500 Exhaust
Ford Racing Brembo 6 Piston Brakes
Boss 302 Steering Wheel
Advantages: The GT will sound much better, be much faster, and look nicer than the FoST.
Disadvantages: Insurance cost is another $100 a month. Mods are a few thousand more, the car is a few thousand dollars more than the FoST, and the interior is very poor compared to the FoST.
Last Option: 2016 BMW M3 in Fashion Grey through BMW Individual with the executive package on HRE P101 wheels. This will leave me with not as much money as I should probably save each money but maybe a whole lot more fun.