This is the perfect intake upgrade for the Audi S4 and S5 (B9). It flows 31% more than stock, reduces pressure drop, and improves turbocharger efficiency. This directly translates to +19 AWHP and +20 AWFT-LBS of torque on top of our Stage 1 (93) tune making this a simple upgrade for more power you can feel, and does so at an incredible value. Our system is a full upgrade as it replaces all of the intake components from the inlet scoop all the way to the turbo inlet. This is extremely important as focusing on the airbox alone does not address the main restrictions found in the factory intake system. Simply put, our system flows better than stock, makes more power, puts less strain on the turbocharger, looks great under the hood, and enhances the sound of the engine. The factory turbocharger inlet pipe is a big restriction point because it's small. It's common for most intake systems to only focus on the filter and airbox, but doing so only has minimal impact on performance. Furthermore, upgrading the turbocharger inlet pipe only has minimal impact on performance if it still necks down to with the factory or aftermarket intake airbox. We solve this by making our pipe as large as possible from the 4" filter outlet all the way to the turbocharger inlet in one piece! This minimizes pressure drop and increases flow through the system far better than a multi-piece solutions. Our system is made from PEX and looks great stunning under the hood, matching the texture of other components. By using this material we are able to make the wall-thickness of the tubes smaller, maximizing the internal diameter, increasing performance even more! The material also allows us to make complex organic shapes necessary when working in a tight engine bay. The airbox is fed from an inlet scoop that maximizes the flow path into the airbox. The airbox has cutouts allowing for additional flow paths directed away from the engine. This keeps air temps down, and increases sound without it being overbearing. The filter is massive as well. A big filter is desirable as increasing filtered surface area keeps the filter breathing easily for many miles as it filters dirt, dust, and particles. It measures 7" by 7" with a 5.5" frontal inlet, and a 4" outlet. The filter media is a washable pleated cotton gauze that can be cleaned for extended life, or replaced with ease. Our kit includes everything you need to bolt on and go. No new tuning is needed to run this product, and the product is emissions friendly. We include all new OEM gaskets and all the nuts, bolts, and clamps needed for an easy install. Lastly, thanks to our billet turbo inlet adapter, this is the only intake you'll ever need. Should you later upgrade your turbo, a new, larger adapter can be installed to adapt to the larger inlet simply by swapping out the billet adapter!