Cobra blower pulleys. 2.81 Vs. 3.10

I was looking on Mustang Tuning for the Steeda blower pulley. I ordered the 3.10 because it said I don't need a chip or new belt with it. I read on here that several of you guys have the 2.81 pulley. When I went to Steeda's website, they said you have to get a chip regarless of which pulley you get. I'm just confused because one site says I don't need a chip and another site says I do. Anybody else using the 3.10 pulley?????????


Mustang Tuning's website:
http://www.mustangtuning.com/st20copu3.html

Steeda's website:
http://www.steeda.com/store/-catalog/03CobraPulleys.htm

Nevermind.... I found this thread.............

http://forums.stangnet.com/showthread.php?t=375637&highlight=3.10