Supercharger Pulley Ring (Ring Only) 1999-2004 Lightning, 2003-2004 Mustang Cobra These pulley rings are designed for use with Metco Motorsports two-piece supercharger pulleys. If you already have a Metco supercharger pulley on your Lightning or Cobra, one of these rings is all that is needed to change the boost level on your vehicle. These pulley rings will bolt to your existing pulley hub using the same (4) fasteners, and no special tools are required for the change. Our pulley rings are precision-machined from billet aluminum and then black anodized for long lasting surface protection. Listed below are approximate boost gains that can be expected when installing these pulleys on a Mustang Cobra: MUPR2.70: +5-6 lbs MUPR2.80: +4-5 lbs MUPR2.90: +3-4 lbs MUPR3.00: +2-3 lbs The 3.65" pulley ring is offered as an option for Cobra owners using our overdrive supercharger pulley but need to return to the stock boost level. This pulley ring will fit our 4-bolt Eaton pulley hub only. We recommend the use of our Auxiliary Idler Kit with these overdrive (smaller) supercharger pulleys to maximize belt wrap and to minimize belt slippage. These idler kits are available for the both the Cobra and the Lightning, and are listed elsewhere in this section. Please see the Belt Length Recommendations link on our home page for the proper belt lengths when using one of these pulleys. Kit includes (1) pulley ring.Learn More