I've got a 99 4x4 cummins. Trucks basically stock other than small things like exhaust and lift pump. I was curious to see if it would hurt anything if I ran a 7 inch spectre filter directly off the Turbo. I'm pushing about 30 lbs of boost

 

Cold air intake don't exist when a turbo produces 300-400*F temps after the turbo.


So I would worry more about the intercooler performance or watch the IAT temperatures more than wasting money on a cold air intake.

Typically my IAT temps float about +40*F over outside temp. The better MPG are found around 100-140*F typically.