One of the first things I did to my sled after the HPS can was a Timbersled clean air intake kit. I highly recommend, lose weight, add some ponys, and I store my spare belt and shovel where the air box use to be. The kit comes with two vents but I wanted more. Vent kit prices remind me of sunglasses pricing, but I can't make sunglasses. Mark out where you want the vent on your plastic and cut the hole. I used a dremel. Then I used a piece of 26ga flat tin ( any HVAC shop or roofing company). Outline your hole on the tin and cut out a frame 1/2" bigger than the hole. You'll need two, inside and outside. Mark both tin frame pieces and plastic for rivet holes and pre drill. Use the frame piece to mark out the vent covering. I used the material off an indoor speaker cover and it has worked flawlessly. Lots of options, use your imagination. Wrap the material around the outer frame and attach. glue or silocone works fine. I used a hot drill bit to melt a hole in the nylon mesh where the rivet goes. Put one frame piece on the inside the covered one on the outside and rivet into place. Total cost, less than 5$ per vent. Use the money you just saved and get one of those 377 belts before they're gone. And thanks for all the info on the C3 kit. I'll be getting mine next week, and after reading all the good advice I will be making my own straight post. A real pleasure being on this site.