I had a Injen CAI for at least 2 months now and i love it. My questions is, what is the size of the Air filter on the Injen CAI? Do you think I can use a K & N filter of similar size as a backup?

I have asked this before and the only answer I received was, I google Injen air filter and it came up with a bunch in 60 sec. Not the answer I was looking for.

Later
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'03 Base 350Z Injen CAI, Hotchkins sway bars Future FI - Nissan GTR

 

Cone filters, such as below, are based on the flange size. Just remove your filter, and measure the outer diameter of the inlet tube.

http://www.realtruck.com/productline...itqKv_AyCxirIS

 

i pretty sure it is 4.5" i have the same intake. $40 for a replacement filter