I had the ATR front mount IC and the optional BOV. I liked the sound, made me smile. Better than brbrbrbrbrbrbblah. The ATR unit quickly rusts its bolts, and is not the best looking unit out there, but does have a big valve, and is adjustable. I am currently getting together some pieces to put on two OEM Subaru BOV. Many have a recirculation port in addition to a port to vent to atmosphere. The recirculation feature is for cars with MAF sensors,(plumb into turbo intake to recirculate the air round and round) But the TRs have a feature that ignors the MAF when returning to idle TPS, so that feature will do nothing. None will be a bolt on. You will have to weld/grind. A pretty unit is from Turbosmart, also has a big valve.
Scott