I wouldn't think there could be "too much". A stock or mild engine has 18 to like 22 or so hg. The more the better IMO because a good strong vacuum signal leads to good street manners and the ability to run power accessories.
A good friend , called ''mr chevrolet around here'' said that anymore than 10 or so would/could start sucking oil thru the valve guides >hi perf. engine ...
no power brakes ,and everything is controlled by the fast fuel inj set up ....
