Look at the ends of the upper air box cover and you see one end sits about four inches higher then the other end. Do you see the 5 plastic ribs on this side? You will need to remove the 3 middle ribs. Cut them off and file them down so that the outside of the upper air box is flat (flush) at this location. I used a dremmel tool and a utility knife to do this. Only remove the three middle ribs. Leave the extreme left and extreme right ribs untouched.
Drill a 2-1/4 inch hole in the upper air box where you have just removed these 3 ribs. Center this hole as best you can, as the ABS Male/Female pipe coupler will be mounted through this hole. Using your round rat-tail file, enlarge this hole for a friction fit of the threaded male end of the pipe coupler. Then clean up any filing debris from the hole.
Place a 1/8 inch bead of RTV along the inner flange of the male end of the pipe coupler (where the threads end and the body begins) and then slip the male coupler through the hole from the inside of the air box.
Place a second 1/8-inch bead of RTV on the threads of the male coupler where they come through the air box on the outside.
Thread (you thought I was going to say "Screw" now didn�t you?) the female end of the coupler onto the male end from outside the air box and tighten it down. Make this tight!
Run additional beads of RTV along the inside and outside of the airbox
where the new air outlet horn meets the air box and smooth the RTV with
your finger. Set box aside for a few minutes to dry.
Modifications to the upper and lower air box are now complete
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