Originally Posted by jlbreaux
what is the difference between the K&N air filter for the 6.6 LBZ and the Donaldson Air filter?
The Donaldson is what is installed at the factory, it flows and filters the best, the K&N is covered with oil that makes it into the MAF sensor which screws up the readings it is sending to the ECM. As for the air box mod it removes that fan looking thing and let's cold air from the fender make it in the box eaiser. A aftermarket cold air system do not add HP, just let's the eng breath better, as I can see it when I did my first dyno run with the factory box then the AFE system, but spool up time seemed shorter or I thought it did