The Kompact Shortie may be small in size, but it's big on quality and performance. The Shortie is a direct replacement for the Mustang EcoBoost's standard blow-off valve. The Plumb Back is a fully recirculating valve, so all vented air is routed back into the vehicle's intake. The Plumb Back offers all the benefits of a Turbosmart BOV, but with quiet operation, so it doesn't attract any unwanted attention.