turbo: blow thru vs. draw thru

Another question: When your full on boost in a draw through and you let off the gas, ie hit the traps and take your foot OFF the gas, where does all that suction go from the wheeling compressor? I can imagine that it would pull the guts out of whatever is left in the fuel bowls through the idle slot creating a very lazy (if at all) deceleration...? I see the wastegate but I dont see a blow off? And if you blow 'in' the intake (vent to atmosphere) thats just not right. Rethinking......:wtf: