My G35 vs a 2006 honda civic si?

I have had my 2005 g35 coupe 6mt for about half a year, I have already put an exhaust and more stuff to it.im sixteen, and i honestly really do like my car, but i saw a guy that has a beautiful civic si with headers exhaust and alot of other things. My car has 66,000 miles and his has 60,000. I was thinking that maybe i will have a better insurance quote with the honda than with my car.he says that he will do a straight trade. Should I do it or would keeping my car be better. like performance wise,insurance milage and other things like that. thank you.