The K&N 57-1129 is a performance intake kit for the 875cc engine in 2011–2014 Polaris RZR 900 and Ranger RZR 900 models. It replaces the factory air filter and intake tube with a roto-molded tube and a large cotton-gauze filter, and K&N states the setup is engineered to increase horsepower and torque. The oiled cotton filter is cleaned and reused instead of replaced, which avoids recurring disposable-filter costs over the life of the machine.
Compared with a stock airbox, this kit is built for higher airflow and stronger filtration, and K&N backs the gain with a guaranteed-horsepower claim and a No-Hassle Lifetime Limited Warranty. It carries a CARB EO number, which matters if you ride where emissions-compliant aftermarket intakes are required. Before ordering, confirm your exact RZR 900 or RZR XP 900 variant and model year against the manufacturer's fitment list, and plan on a short, bolt-on install with basic hand tools. Searches for "RZR 900 875cc cold air intake," "2014 RZR 900 EPS LE intake," and "K&N 57-1129 install" point to exactly this kit.
The manufacturer states the kit is legal for use in all 50 states and lists CARB EO number D-269-51. Confirm any local requirements for your specific machine before installing.
The manufacturer says the kit replaces the factory air filter and the factory intake tube, so the stock components come off during installation.
The manufacturer gives a cleaning interval of about 100,000 miles under normal highway driving conditions. That interval does not address dusty trail riding, so check the manufacturer's care guidance for off-road use.
Per the manufacturer, a typical installation can be completed in 60 minutes or less using simple hand tools. Because the kit replaces both the factory filter and intake tube, plan to remove the stock air components first, then fit the new tube and filter, and confirm the clamps and hose connections are tight before riding. Owner-reported installation gotchas were not confirmed during research, so review the manufacturer's installation instructions before starting.
