http://www.henley-tvr.com/new/speed1.../speed12_1.htm
Check out this link to an article on the TVR Cerbera Speed 12. I know it's not a Mustang, but it's a pretty crazy car (if you've played Gran Turismo 2 much you know that it is a bad mother). Car only weighs a little over 1000kg (2200lb) with an 800hp naturally aspirated V12.