See, the thing most people are missing, is that whether the valve vents to atmosphere or recirculates, that air is not going into the intake anyways. Yes, in the case of a recirculating valve, the air is still in the intake tract somewhere, but this is not a large amount of air, nor does it happen over the course of several seconds. If that was the case, yes, it probably would make it run rich. But, it happens for a split second and it is a very small amount of air. And, the valve opens when you let off the throttle, which tells the ECU to cut the fuel anyways. So, no, they don't make any car I've ever had a wideband on run rich. I don't claim to know how they work on an Eclipse, or on a Supra, or any other turbocharged car, but on a WRX, they do not. Period.