right now with a 5 spd im crossing the traps at 109 mph in 4th gear at 6,200(ish) rpm.
this is just an educated guess, but IMHO theres no way in hell an auto is gonna get near those rpms/mph while staying n/a with bolt-ons running 4.30s. i say go for the 4.56s, w/o them, i dont think you wont...