And don't drill extra holes in the air box ! That will bypass the filter.

Removing the snorkel will give it more air (and make sure the air filter opening edge is sealed), but as far as I can gather a too lean setup can also give back firing (loud popping)

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2014 XT660Z - Barrett pipe, DNA stage1.5, Barkbuster hand guards and handlebars, Pivot pegs, Teknik suspension, Guard-it engine protector combo, B&B rear rack, Trax topbox.