if running higher boost than stock using manifolds as a source for fuel regulators , and map sensors used for controlling alky or speed density like FAST /XFI/SD chip and even boost gauge/electric boost controller is a very bad idea
hvac , emmision cannister and even vac brake line are not motor critical in that if a line to them popped under boost your motor wouldnt go boom, but if you tie them to a manifold and loose one of those the engine critical sensors wont see the correct pressure and could result in bad things happening due to the loss of air from one of those lines dropping the pressure in the manifold
map sensor , regulator reference , and boost gauges should be run directly to the plenum or intake
for the quickest and strongest vac brakes the source for that should also be off the intake /plenum on its own line preferably using 3/8" ID through the fitting .those fancy billet vac blocks use an 1/8 npt port . if running high boost a good check valve inline should be used to prevent the booster check from popping leaving no vac assist .
