This page focuses on the items that are included with the B5 A4 Stage III+. Because this kit is so extensive, it would be impossible to highlight all of the items that are included with it.

Exhaust Manifold

The Stage III+ exhaust manifold is investment cast out of Inconel, a high-temperature nickel alloy. The manifold was designed in CAD and optimized using computational fluid dynamics (CFD) software. What this means to the end user is the ultimate in performance and reliability.

Custom Silicone Inlet Hoses

These CAD designed hoses are designed to replace the factory hoses between the airbox and turbocharger, and the turbocharger to the factory cross-over pipe. APR both designs and makes the tooling for these items in house, using a combination of our CMM tool, SLA machine, and CNC machine.

MAF Housing

The mass air flow sensor (or MAF sensor) measures the amount of incoming air and sends an analog signal to the engine computer representing the amount of air flowing into the engine. The MAF sensor is mounted in a cylindrical housing that is sized according to engine displacement and maximum power output. We replace the stock MAF housing with a cast aluminum unit to allow the proper metering of the additional airflow and to minimize pressure losses. The cast aluminum housing is CNC machined to exacting tolerances and powder-coated to inhibit corrosion.

Honeywell/Garrett Turbocharger

Representing the latest in turbocharger technology, a Garrett Ballistic series turbocharger is the only choice for a premium turbocharger system. APR is unique in that we deal directly with Garrett turbochargers rather than buying turbochargers through turbocharger supply houses. Our engineering-house distributor status with Garrett turbochargers means that we receive assistance from the manufacturer on technical issues and work with Garrett engineers on specifying the optimal turbocharger for each application.

Flow Straightener

The correct flow straightener was sourced to ensure laminar air flow through the mass air flow sensor. This is important for proper air flow metering at all flow levels. The flow straightener is sandwiched between the MAF meter and the air horn and is held in place by a retaining clip.

APR Fuel Injectors

APR sent many hard hours with a major OEM manufacturer to develop a fuel injector that has the same spray pattern as a stock injector, but with a very high flow output.