Audi A4 1.8T test pipe are the ultimate way in achieving maximum engine potential. By installing our test pipe, you are replacing the most restrictive parts on the exhaust system. From your exhaust manifold to your cat back exhaust, the catalytic converter restricts air flows which create unnecessary back pressure. To ensure the engine performing at its full potential, upgrading to our straight through test pipe is the best choice. However, our test pipe are for Off Road Use only.