I just installed a S&B cold air kit in my 6.7. In the air filter box of the kit it has an opening at the bottom for air in and side facing motor it has another area that can open or plugged with rubber cap. Do you think it's better with that plug out letting in more air into the box? Or keep it plugged.

 

Keep it plugged. It would be sucking WARM air from the engine compartment with the plug out, defeating the purpose of a COLD air intake.

 

do you notice any difference in the sound of the truck/exhaust?
I would suspect the power gain would feel minimal to the "butt dyno" ??

 

Not really any sound deff. I think if it was open not glass top you would hear more air draw sound. I am really just looking to gain alittle more power and more mpg. Pulling 10k travel trailer. Next programmer.

 

True. Didn't even think about that being on engine side. Lol. Just switched to this truck from 250 5.4. New to diesel.