[SleepR 240sx]

Vaccuum level is good so prolly no leak there. Venting the BOV to atmospohere will cause you to run a little rich, possibly cause your car to stall when putting it in neutral to come to a stop. Sounds like it could be a MAF problem, run up to autozone and get some MAF cleaner and spary the leads and all with it, let it dry and see if it makes a difference. Also could be an exhaust leak, if there's a big enough leak you could be losing enough pressure that it's taking your tubo longer to spool up and would explain the bogging as well. Also, I've run open downpipe on my s13 sr, and it felt more sluggish than with my catback apexi. Prolly due to backpressure. That's just off the top of my head. Hope I helped.