After reading MXA article on the air box mod as seen on Ryan Dungey's bike utilizing the 350 air box I came up with a full proof process if you want to perform this mod. MXA believes the air box mod increases low to mid range performance. First of all you need to purchase two items; # 1 is a 2013 ktm 350 sxf air box, this box is a long and straight tube shape as opposed to the open giant box that comes stock on the 450, #2 is a product called Cool Chem, it is one of the greatest products I've ever found. You can literally weld rubber, solid and air tight. MXA says you need to add 2" and they used super glue. I question their process and reasoning. If you take the stock air box and cut off the large lip at the end of the box, approximately 15 mm of it and cut out the oil vent nipple (leaving a little bit of rubber on it for a bonding surface. Now line up the ends on the 350 air box and the 450 air box, apply the glue like product from your Cool Chem kit and then spray the activator. The two pieces will be glued to gather perfectly and so tight you won't believe it. Next, I trimmed out any rough edges at the new lip. The new length of the boot is long enough now to reach the throttle body. Change out the air boot, this is a long laboring process, just take your time and be patient. Once the boot is mounted just push the end of it over onto the throttle body. You will have to force it over a little but once it is there it will clamp on perfectly. Take the oil vent hose and find the perfect position for the nipple to attach. Mark it with a magic marker and yes take it all back off so that you can drill a hole for the vent nipple to fit into. Don't forget to clean and air blow any lose particles out of the air box from the drilling process. After you have trimmed off almost all the rubber around the original nipple (not an easy task) apply the glue like product from your Cool Chem kit and press the nipple in and apply the spray activator on the inside and outside where the nipple goes in. It will set up air tight and you won't believe how well it will hold. Now put everything back together one last time and secure all the clamps, bolts, etc... If your not good at mod's don't attempt this, but if your not afraid to work on your own bike, this mod works and is not all that bad. Just plain on a few hours of patient disassembling and reassembling time. Good luck and I hope someone finds value in this process.