What is the reasonable life expectancy of my Ford Mustang?

I have a 2006 ford mustang gt convertible. I love it and it is in wonderful condition. I'm at 126k miles and I'm thinking about dropping in a factory style nav system. This will cost me 1000k. This will give me all the modern stuff, back up camera, bluetooth, ect.

Should I dump this kind of money in this car? I work in the oil field so buying a car at this moment is out of the question. You think I could take the mileage to 300k?

Read more: What is the reasonable life expectancy of my Ford Mustang?