i dont think that its underpowered… i just think that its way way over weight to be a performance car. its a freakin boat.
and yes it needs 19’s atleast… atleast other 18 GM wheels dont fit. i would like to see a low profile 18 (meaning the inside of the wheel is not so chunky) come out because i would rather have 18’s on it… or shave some of the caliper off of it like the ls1 guys do to fit 16’s or 15’s i forget