I've been searching through the forums for an answer and I can't find it so I figured I'd post it.

I've been reading through my haynes in my boredom and I came across setting engine idle speed.

I know its great for constant stop and go conditions to keep it at factory, but what would the effect of setting it to high or too low be?

 

if your car is idling fine, dont even mess with the idle. setting it too high, or too low doesn't give you any "gains" if that's what you're implying.