Is the 16V 928 engine designed for a low vacuum at idle, or is it for emissions?

Can there be too much vacuum at idle and damage the engine? Eg. will an increase in vacuum pull oil past the rings?

I have removed/plugged all of the vacuum robbing items from the throttle body. My vacuum at idle has gone from ~17 to ~20 inches, with a noticeable improvement in response. But is there a downside?

Removed:
-Vacuum limiter device
-Carbon canister, hoses, gas tank vent line unplugged at rear wheel well after safety valve
-Venturi Y-connector, direct hose from plenum to brake booster
-Retard hose to distributor
-Air pump

PS: I try always to transition slowly as much as possible from cruise to idle (on any car).