AIRBOX
NO! You can gain some just a squeek, but it is give and take...try to have your airfilter held in place and run without the lid...it just doesn't work. Everything is give and take. Replacing your airfilter with a good one is the best thing that you can do. Looking at it from another win/lose situation...if you have an airbox and it rains or it is muddy the water or mud settles to the botom of the airbox and if you are just running airpods they don't have the restrictive passage so the water, mud sand, dust goes directly to them and you are replacing them more often and or running to rich because they are plugged up or very dirty in just one pass. If you change to airpods or go to extreme no lid or open up for to much air you will be running to lean. Just like an airplane engine or a car engine even your bike it will run to hot. then you run into pre-ignition and all sorts of bad things. You can change the running lean to normal settings by readjusting or rejetting your carb(S). same thing if you change out the entire exhaust system. everything has to be run so that the fuel/air mixture is at the correct ratio. it's hard to explain, but even race cars at a local race track will be adjusting their carbs before a race because the change in Barometric (weather or altitude) changes. If you set up your bike, tuned it perfectly in SanDiego, California (Sea Level) and then put the bike in the truck and took it to Denver, Colorado, it would have to be tuned again. THe carbs can't adjust themselves like the Electronic Control Unit (computer), and Electronic Fuel Injection can. The old fashion racers still like Carbs that you can adjust to a very precise setting depending upon lots of factors like the actual fuel being used, the blend of it and so forth that an O2 sensor couldn't sort out. Alcohols, and other things used in racing fuels... anyway...in short...just get a great filter, keep it very clean, and adjust your carbs........