Fitment: Part #:1891-K1 UPC: 600209905511 Fitment: 2012-2015 Honda Civic Si with OEM intake manifold and OEM throttle body Part #:1891-K2 UPC: 600209905528 Fitment: 2012-2015 Honda Civic Si with OEM intake manifold and ZDX or similar big bore throttle body Part #:1891-K3 UPC: 600209905535 Fitment: 2012-2015 Honda Civic Si with RBC or similar intake manifold and OEM throttle body Part #:1891-K4 UPC: 600209905542 Fitment: 2012-2015 Honda Civic Si with RBC or similar intake manifold and ZDX or similar big bore throttle body ***************************************************************************************************************************************** An Exceptional Intake System, Built on the OEM 2.0 mindset: Nearly 1.5 years in the making, the ACUITY CURL CONTROL Cold Air Intake system was designed and painstakingly refined to be the best performing cold air intake for the 9th Generation Civic Si. Perhaps just as important, it was designed with careful attention to how it integrates with the OEM chassis mounting points and electrical connections. It is built from superior materials and requires no cutting or extending of OEM wiring and no clutch system bleeding during installation. The kit is designed to be incredibly complete, meaning a very simple installation. Air Handling: With its hand-laid carbon fiber and bonded billet 6061 aluminum appointments, this intake's carbon tube is the centerpiece in both performance and appearance. Air enters through a large, 6" dry filter, mounted to a spun aluminum velocity stack that reduces to 3.5". The silicone couplers located on either end of the carbon tube are designed with reliefs to provide a smoother transition as air enters and exits the intake. The throttle body coupler features an integral aluminum hose barb. Silicone hoses are also provided for the valve cover breather and coolant bypass. The carbon tube features a bonded billet 6061 aluminum MAF mount and mounting boss, both anodized in ACUITY's signature purple. Also supplied with the kit are German-style hose clamps. While more difficult to tighten compared to traditional clamps, German-style clamps provide more even clamping and have formed threads and rolled edges to prevent damage to the silicone couplers. Battery and Wire Management The supplied battery tray is both attractive and durable. This is thanks in part to the careful combination of stainless steel and aluminum, allowing it to be strong where it must and light where it can, all while providing a rust-resistant design that will age gracefully. With laser-etched wire routing callouts and integral mount points for the battery ground and all wiring extensions, the battery tray ties the CURL CONTROL kit together to make it the most well-integrated 9th Gen Civic Cold Air Intake kit available. No wire cutting or splicing is needed. Instead, wire extensions are supplied to allow plug and play installation. Tuning and Performance The CURL CONTROL intake is designed to reduce pumping losses and reduce negative Helmholtz resonance effects to provide improved power and more desirable torque and power curves. In both internal and independent testing, ACUITY found the CURL CONTROL intake to produce 5-10 peak horsepower over the leading 3.5" aluminum cold air intake systems and up to 5% more area under both the power and torque curves, meaning more usable power, especially when compared to the stock airbox. Additionally, the CURL CONTROL intake helps to improve low-end torque and reduce the torque dip seen in almost all other intakes in mid-range RPMs. The result is an intake that not only provides impressive results over the stock airbox, but also impressive improvements over competing 3.5" intakes. Because the CURL CONTROL's intake has a full 3.5" inside diameter, the air velocity is reduced compared to stock, and the factory MAF calibration will cause the vehicle to run lean. For that reason, it's absolutely essential to use a tuning solution like Hondata, K-Tuner etc. to account for the increased airflow to the engine. If temporarily running the car on a base calibration, make sure that the calibration is at least proven to work well with a full 3.5" intake. Upgrades Made Easy With the variety of intake manifolds and throttle bodies available to 9th Gen Civic Si owners, we know that there are good odds you'll want to change one or both of those components down the line. We're here to make those mods easier. ACUITY sells the throttle body couplers for each kit separately so that if you ever change your manifold or throttle body, you can simply buy a coupler and upgrade your original CURL CONTROL kit. Kit Contents: (1) Bonded Carbon Fiber Tube (1) 5-ply, Fiberglass-Reinforced Silicone Throttle Body Coupler with Integral Aluminum Hose Barb (1) 5-ply, Fiberglass-Reinforced Silicone Elbow (1) 6"-3.5" Aluminum Velocity Stack (1) 6" Cone Filter (4) German Style, Stainless Steel Hose Clamps for Intake Piping (2) German Style, Stainless Steel Hose Clamps for Valve Cover Breather (1) Silicone Valve Cover Breather Tube (1) Coolant Bypass Tube (1) Stainless Steel and Aluminum Battery Tray (1) Intake Mounting Bracket with rubber isolation mount and hardware (1) MAF Harness Extension (1) Battery Sensor Harness Extension Fitment: 2012-2015 Honda Civic Si (with an RBC or similar intake manifold) Important Note About Aftermarket Motor Mounts (PLEASE READ) The CURL CONTROL battery tray has been confirmed to fit when used with OEM and Innovative motor mounts. The kit is not plug and play with Hasport mounts. A small amount of grinding on the Hasport chassis-side transmission mount will allow the battery tray to be mounted, but it is ultimately the end-user's decision whether or not to do this. Important Note About Aftermarket Batteries (PLEASE READ) The CURL CONTROL battery tray was designed for use with an original equipment sized battery. Larger batteries may create fitment issues.