Dear Ed;
It's the old "titer-totter" theory. Whatever you add to the 'top end' you subtract from the lower.
I don't know of anyone that builds a 'Hot Rod' engine that is concerned about the idle when runing a standard transmission. Once your above 1500 RPM It's all academic anyway.
Personally; I want all I can get in the higher RPM ranges and that means a lousy idle.
Remember, engines are not made to idle, except at stop signs.
Good luck.
