How much better is say an injen or typhoon intake than the ol reliable airbox mod?

Also what is the diameter of the stock intake tube vs the 3in of most intakes?

 

I went from an air box mod to a AEM adn only noticed a sound difference. I doubt there is more than a couple HP difference between an full CAI and a good airbox mod. If your running a 2.8 or smaller pulley you might start to gain more with a CAI......... if your running a stock or stage 2 pulley, save the money for something else. I'm pretty sure the K&N and injen intakes aren't 3 inch , i think they are 2.75"