personally i wouldnt do that.

the vaccume created by the manifold is deisnged to suck out from the crankcase at a certain rate. also the pcv valve itself has a spring ball mechanisim that moves up and down as pressure increases or decreases.

if you change or otherwise alter the pressure you could damage your crankcase (due to mis-ventilating) or blow apart your pcv valve.

I had a pcv valve literally blow apart from a clogged line that goes from the pcv to the manifold. the line was clogged causing the pressure to jump too high and sucked the metal part right out of the plastic valve.

my suggestion. just leave it alone. get a new pcv valve and some new tubing, preferably fuel line tubing, its thicker, more durable, lasts longer, and better for heat. Clean everything out and youll maintain a good vaccume from your manifold. No reason to go above and beyond when you dont need to.