04 Pulley Sizes/HP Gains vs Stock


New Member
Jan 25, 2007
Fort Collins CO
Hey guys I am going to be getting a stock 04 Cobra in the next few days and had some questions regarding pulley sizes. Do you know the stock diameter, and typically how much HP do you gain as you get smaller? Any recomendations on pulley size/brand and belt brand. I have heard that some belts hold up better than others. Thanks for the info, hopefully I can get some pics up real soon!
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The factory blower pulley is 3.65". I would recommend going with a Billetflow 2.76 upper pulley and Gates belt.

Als I would recommend a set of idlers to go along with it. A snub idler is needed to help avoid belt slip and the other idlers should be replaced as well. I have seen too many stock idlers fail and destroy anything in their path when they fail. Including radiators, powersteering fluid reservoirs, etc...

I would give Lethal Performance a call. They can help you get what you need. :nice: