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Free flowing filter = more air , more air requires more gas , that's where you get better performance . Larger jet gives more fuel and also prevents a possible lean mixture situation that can and will damage your engine . Jet size choice's can be tricky / trial and error . Go with advice from someone that's Been through it with the EXACT Buggy , filter , etc. But circumstances can vary . Only the color of your spark plug knows for sure . Learn what that means and you'll understand proper jetting . Like any hobby the learning curve is a lot of the fun . Get an education on your carb.( simple ) and what I said about spark plug color and then you can make a better choice between DIY , or shop . Regardless it's a 1-2 hour job . Hope this helps . And seriously check your tire pressure , and other things I mentioned . Low air pressure in tires steals tons of power .