Personally, I think its a great accomplishment to be essentially debt free (excluding normal bills and house payments) and it sounds like your almost there with your current car. I would ask yourself, what am I really going to be using the car for? If you plan on taking it to the track and running the piss out of it and really need more power, then I can see you buying the new one. But if its just going to be cosmetic like you said your current car is, I would assume that you are just having the car for cruising and enjoying, then I would keep your current car. I was in the same situation as you before I sold my 09, but I wanted to start to be debt free so I can finally get out of my parents 'care', so I sold it and paid cash for a good used f150. Now I can just concentrate on other bills and not worry about the car.
Personally I say keep your current car, I like the 5.0's but for my style of driving I dont need more power than the 3v has, plus the new ones are still ass end ugly. lol