On naturally apirated cars, having lower gearing is better, but I've read a few times that turbocharged cars like a load for best acceleration. Some Grand National guys tried putting lower gearing in their cars and actually found that it slowed the car down slightly. I guess the turbo won't spool as quickly when using lower gearing, or at least it doesn't stay spooled as long in each gear, lowering the average power output of the engine.