Contrary to everyone dissing the G8, I actually own one. 80k miles, only issue was an alternator going bad. No "rattles" as another member says. The FTI billet converter and a good tune will make you think twice about ever driving a stick again. DOD is easily removed, and gives you a chance to change the cam for a big power gain. My car has ran a 12.1 with a 1.7x 60ft and I still alternate daily'ing it along with my truck with no issues. Made 30+ passes this summer and drove thousands of miles with 0 issues.
OP, if you are interested in driving a modified G8 PM me when weather clears up.
I looked at all your other choices before buying my G8, and I drive customer cars daily.
GTO- suck ass rear end, shitty interior, can't fit a big tire.
V1- Extremely dated interior/exterior styling. Eat rear diffs and bushings for dinner.
5th gen- piss poor visibility. Ugly ass interior "retro" styling