Help with convincing my dad

I know exactly where you're coming from, I'd get the GTP and mod that.
I'm the same age as you and was thinking about leaving this stock and waiting for a T/A, but the gp is more than good enough for me right now, and really, what do kids our age need two cars and a car payment for lol.
I went with topswapping my GT because I don't want to sell my car and it's got higher compression, honestly GTP would've been easier though cuz I have no mechanical knowledge lol but whatever its almost done now (I've got all the parts, just waiting for SOMEBODY that get help me with the actual swap).