What size intake pipe?
 

So I have a 3" dia CAI pipe in my car. But I'm trying to look into this and cannot find too much on the matter. I can't even find the pipe diametes companies like K&N use for CAIs. Should I go down to a 2.5" or is 3" good? Does it really matter?

What matters is the intake resonance, and that all depends upon the design; most likely the factory intake was optimized for mid range torque; who knows where your current intake hits its optimal resonance.

I made it so I doubt it. However, it is possible to mimic the brands.

My AEM short ram intake for my 96 Accord is 2.5" in diameter. I'm pretty sure the K&N and Injen ones are the same as well. I'm sure R&D showed that that was the best diameter for all around performance.

Ok. Thats what I was thinking but wasn't too sure. Thanks.