Ah, air cleaners, the other half of the quick-and-dirty bolt-on horsepower duo for your motorcycle. Whenever someone buys a new V-twin, the stock airbox and exhaust pipe get relegated to the dark underworld of being sold to a stranger on Ebay to offset part of the costs for their higher performing aftermarket counterparts. It's just one of those time-honored tradition things going back to not only the days before Ebay, but home computers in general. That's because better breathing works. More efficient intake, more efficient exhaust, more efficient motor; it's that straightfoward. Bolting a new set of pipes and an air cleaner is also really easy. Like, do-it-with-cheap-Home-Depot-tools easy. For 15-20 minutes work with simple hand tools you should have around the house anyway, you get a noticeable bump in power for your motorcycle (assuming you've done your homework and figured out what pipe/airbox combo is best beforehand). Below we've cobbled together a little guide to nine air cleaner options for your consideration.