HOW THE HELL ARE WE AT POST #26 WITH NO CARRERA GT!?!?!?!?!?!?!?!?! Hands down my favorite howl. Otherwise yes, pretty much anything Ferrari + the LFA.
On more plebian levels, BMW's I6's (particularly M varients) are the closest thing an old school GT racer sound that you'll get, IMO. They're not for everyone, not everyone enjoys that raspy howling clamor when you ring it out, but there is some level of mechanical aural pleasure listening to that symphony.