Pulley Upgrade for 03-04 Cobras. Upgrading to a smaller supercharger pulley on a 03-04 cobra is a very popular modification. Most people end up going with either a 2.76/2.80" pulley. That will increase boost from the stock 8psi to 14-14.5psi. There's two types of pullies you can go with. One of which is a single piece pulley such as the Reichard Racing pulley that gets pressed onto the snout . The other style is a hub and pulley ring setup such Billetflow or Metco. Those setups use a hub that presses onto the snout of the supercharger and comes with a ring that bolts onto the hub. The benefit of the hub and ring setup is that you change pulley sizes by simply swapping rings. Not only can you change the pulley on the supercharger but we also offer lower pulley kits which replace the stock lower pulley for one which is larger in diameter. So depending on how much boost you want to run you'll want to order the correct upper or lower pulley size for your specific setup. A few other things that we recommend you do at the same time of the pulley swap are a custom tune, intake and a set of colder range spark plugs. For the custom tune we offer Jon Lund custom tuned SCT devices. These come pre-loaded with a custom tune specifically made for your car which you plug into the OBDII port. From that you can flash the tune onto the car's PCM within minutes. For the cold air intake we recommend a higher flowing less restrictive intake such as the JLT Cold Air or Ram air. These will increase air flow to the supercharger and help the engine breath better. For the spark plugs we've had great success with the NGK TR6 copper plugs. The iridiums work well too however the copper plugs can't be beat for the money. The TR6 plugs should be gapped at .035 with a pulley setup such as a 2.76"/2.80"