I simply used a holesaw to cut an opening in the opposite side of the airbox. Used a threaded black PVC pipe I nutted to the inside of the airbox , glued to an elbow with a short piece of straight pipe glued in the other end to hose clamp connect a section of flex hose from it to another short nipple glued into a 45 degree fitting which short nipples into the opposite end of the existing upper air box. I hole sawed additional holes in the leading edge of this box that I can duct tape over to fatten a jetting or open up to lean it. This was a pretting inexspensive mod. that really works well to aid giving the 350 or Pilot more air. On the Pilot I attach the fitting in the lid instead of the box.