I just finished modifying the airbox on the WR450. After close review and removing the snorkel as everyone else did, I noticed that the seat bottom has a large protruding bulge that nearly seals off the 2 main air intake openings next to the battery. I looked at the rear fender as it contacted the air box and using a dremel grinder cut away the air box up to the two extruded flanges for the battery tray bolts. This creates a nice 5" wide x 2" high arched opening. Now I had to dremel grind the battery tray/ air box lid. I cut away the rear half on both sides where the old snorkel fit into and left a 1/2" wide strip down the middle where the center support bar can remain to support the battery wall. I beleive that a single centered large opening creates the best air flow in the rest of the box. After slotting the left rear number plate to match the right side, I can now look in both number plate slots and see the entire bottom half of the air filter. I relocated the coolant lines and I will relocate the electrical connector just in front of the battery before I am complete. I am by no means an expert at bike set up, it did not take much analysis to figure out that the bike was starving for air. I just did not like the idea of drilling holes in the side of the box. The battery has to stay I love the electric start. I wish I could attach images but I do not have a server to put them on. I will email pictures to anyone that would like to see the mod and they can post it if they feel it is worth while.