Originally Posted by NOS327
No. I mean a silicone hose/elbow that would mate your air inlet duct to the throttle body. Not the tb to intake o-ring.
Sorry, my bad - I saw the word silicone and was thinking silicone seal. In any event the answer is 4.0 inches. I am running a 90mm LS2 DRW and it measures 3.960 at the inlet, which includes a slight lip. (This is the same as my stock LS6 DBW 78mm throttle body which allowed me to use the same inlet air tube when I upgraded.)