a pcv system is a big vac. leak, if it could pull the brake booster down then it couldn't be sucking the fumes out of the oil pan at the same time. the brake booster has to have a constant vac. on it to work and a pcv system is not a constant vac. it can not pull the brake booster down and suck the fumes at the same time. i dont know what you're doing, but something ant working right. you cant tee nothing into the pcv hose but, you can the brake booster hose. if your hoses is run like that diagram looks, you wont have proper brakes.