I have a UPD which is the best CAI intake in my opinion...
I have had it on 4 of my trucks now..
I was looking at Vararams web page and see they offer a CAI for a Duramax..it is the lower unit of the stock box that is replaced..I think this should hook up just fine to my UPD..sence I have looked at my dads duramax intake it looks like the same lower box as my..as is all GM trucks that I have been around..

any suggustions..Im thinking I will do this it looks alot better than the stock lower unit anyways and only cost $75 ..

by the way I just put my 4yr old UPD on my 6.0 yesterday and MPG went from 12.4 to 13.1 in just 2 tank fulls

 

i would just cut the bottom out of the stock airbox for free.

 

Although cutting your airbox migh be an optin i would think this lokes cleaner , plus without the ribs and stuff inside the airbox to lower noise. It would net you a small gain probably not even notisable get a grinder of some kind and smoth out the inside of your airbox

 

with the filter and lid on the intake nobody will even be able to tell that the bottom is cut.