i know this is not quite what you're looking for, but here's an idea.
if you want an exotic sounds, why not just use a VQ35de out of like a maxima and do a custom exhaust? has a FWD tranny that can easily be made to work for a RR car, quite a bit lighter than a V12, and still sounds nice and throaty (ie 350Z & g35). sure it's no V12, but i think it will be powerful enough to propel that there fiero, and it will be lighter for better balance.