The outlet diameter of the AWE Tuning downpipes is ~2.1875" in order to mate up to all known S4 exhaust systems on the market.

However, upon ordering a full turbo back exhaust system from us, consisting of the AWE Tuning downpipes and AWE Tuning Twin2 exhaust system, we now offer to match the downpipes and exhaust to reduce the slight bottleneck and maintain a 2.25" diameter at this junction. This results in even better exhaust flow and a few more hp at higher rpms.

Please note that this option is only available on our downpipes and Twin2 exhaust system when purchased at the same time. Please contact us if you currently have both our downpipes and Twin2 exhaust and would like to upgrade to this option.