Exhaust

Nothing major, csc, oil temp (if your tracking never gone into limp mode around town), fuel starvation on hard G's below half tank (there is an upgrade for this.), Shitty rear visibility, you develop chronic speeding habits, loud cabin noise, no trunk space, no practicality, blinkers arent loud enough causing you to drive with them on all the time, most z drivers wont wave back at you if you wave at them, too much fun, attracts boy racers, entices people to rev at you at stop lights, a little tough to drive in the rain, body roll needs to be corrected with front sway, and last but not least but I think this is important its just "a little v6".

Edit: Tl;dr auto tranny is bullet proof it will need a tranny cooler if you want to SC or FI.