PLZ HELP!! Loud Squeel OR Howell on turbos?

hey i got a 300zx fairlady and i just did the valve cover gaskets and just put back together now the car runs fine other then the idle wants to bounce around up and down up and down, then smooths out then same thing.so i unpluged the o2 runs smooth now lol..but when the motor is on the road in gear right b4 the turbos kick in, it make a god awfull howelling or whisteling noise from the centre of the dash board and i can't figure it out for the life of me plz plz help any input would be great, remember it happens right b4 the turbos boost then when it boosts it gets louder....:banghead: eventually going away.:screwy:
its a v6 2+2 twin turbo Twin DOHC (right side drive) 5 spd