If you add 150 hp you wont need gears. In fact I ran better 1/4 mile times with stock gear because my car would shift into over-drive(6500rpms) just before the trap.
With 3.27s my 60' were 1.75 with an automatic trans. Any more gear and I would need a larger slick.
i think it has alot to do with the way your power band is set up....if your power band is really strong in the lower to mid ranges sure smaller gears such as 3.27s would help but it your powerband is in the upper ranges i dont see why lower gears such as 4.10s, 4.30s wouldnt help