When the bike is in stock form I was dicking around with the bike last night and took off both the upper shrouds which serve as air box port tunnels on the 2010 yz450. I was removing it cause I figured I would do the air box mod and see how well this would work out and wanted to see where the best place to put the holes would be. I got tired and went to bed and figured I'd do it in the morning. So today I decided to go riding and completely forgot about the airbox mod and loaded the bike up and headed out to my riding area. When I unloaded the bike I realized that I forgot to put on the intake port for the airbox on the right side and it left the right side of the airbox completely exposed. I figured this would be a good time to test out how well the mod would work on my bike cause the whole right side was missing, which in essence would be the same if not better than doing the mod. Rode for an hour and a half and I can say that the bike was def louder on the higher RPM's, very loud. Kinda liked the noise, gave the illusion of more power but I can honestly say that I didn't feel any more power than before... None. I'm glad I did things this was cause I would have added the holes and realized it didn't do anything at all. Now I can put the upper shroud back on for the air box and not have to permanently alter anything. This must work for people with ported engines and/or aftermarket exhaust, cause I didn't notice any difference in performance at all.