Throttle Body to BIG!?

Im trying to understand this. I have heard that puting a 75mm T/B on a relativly stock engine (or engine making 250hp or less) may be better than stock T/B but a 65mm T/B would be optimal and would yield more horsepower and range.
This makes no sense to me. Does anyone no why this is so? Thanks

too much airflow leads to a drop in torque, i wouldn't go so far to say that 65 is better then 70, but either are better then 80 on a stock engine.

For a lightly modded car a 65mm TB will be just fine. A 70mm TB on a lightly modded car will lose a little bit of low end torque. You also have to take into consideration the rest of the engines breathing capabiliies. If the rest of the motor is not adaquit to support the added air flow, in and out, then it's just over kill.