Transform your Arctic Cat 858 into a 200+ horsepower machine with the Straightline Performance Complete Nitrous Kit. Designed exclusively for the 858 platform, this complete bolt-on system delivers an instant 35 horsepower increase while operating on 91-octane pump gas. Engineered for maximum reliability and easy installation, the kit includes everything needed for installation and pairs perfectly with the Straightline Performance Quiet Lightweight Muffler, which is required for proper exhaust flow and peak performance. If you're looking for the biggest horsepower-per-dollar upgrade available for your Arctic Cat 858, this is it.