Value wise if they are both in good shape and close to stock its pretty close. Drive his GT and see what you think I guess but yeah there are too many variables not known. I will say that if you do trade and then there is an issue with one of the cars it could suck friendship wise.
2000 Mustang GT Steeda #0048
Just because I give you advice, doesn't mean I know more than you. Its just means I've done more stupid ****.