I have the a'pexi sequential BOV. It's connected at the y-pipe and at the manifold where-as most bov's connect at the manifold. So is this kinda working as something other than a BOV?(like a pop off?)Under WOT, when the the primary switches to the secondary I hear that BOV blowing air for just a quick second. Is that a boost spike that has come from the y-pipe and is just blowing off? To me that would make sense, and it would be a great reliability mod. I was thinking it may have started to creep and then before it has a chance to do any damage it just blows any spiking out through the y-pipe connection.

 

It sounds like the Apexi BOV has ben set up as the Charge Relief Valve (CRV). The CRV vents boost fron the secondary during the PRESPOOL phase to allow the secondary to get up to speed quickly. the secondary turbo accelerates from low rpm to 120,000+ rpm in 0.5 sec during the prespool.

Also the Primary turbo works all the time - the secondary operates in ADDITION to the primary above 4500rpm