I bought a re-circulation kit for my HKS SQV, but I am not recirculating it back to the intake, the adapter is just on there... in my opinion, I'd rather spit out excess air rather than recycling it, since I have a free-flow filter, it should'nt be too bad to be running rich slightly when shifting gears and I doubt it will kill anything... unless it was too too rich, it might kill your O2 sensor or maybe uppipe [not entirely sure on this one]? but then I have an S-AFC, that should correct it some. I don't like recycled air, its not all that great for the efficient side. Recirculating my BOV won't help in turbo re-spool up response anyways in the way how most of our street cars are set up. You'd need another device to make the turbo keep spinning between shifts, just recirculation won't do at all.