On a turbo engine, the exhaust output at low RPM is much more reduced than a normally aspirated engine simply because the exhaust has to first past through the turbine wheel. The downside to this is, the catalytic converter (a key emissions control device) takes much longer to heat up to operating temperature during warm up. For this reason, the factory places the cat converter as close to the exhaust manifold as possible in order to scavenge more of the exhaust heat and energy at the source in order to warm up the cat converter quicker, and to make it more effective. On the 2.0T engine, the cat converter is placed so far up the stream that it's directly behind the turbo's turbine wheel. While this placement is good for the cat converter operation, it's truly detrimental to the turbo performance. With air flow out of the turbine wheel smashing directly into the face of the cat, overall turbo efficiency is drastically reduced. Our stainless downpipe utilizes a large diameter 3" pipe at the turbo flange and removes the cat converter. The area immediately out of the turbo is the hottest, most flow intensive, and the area of highest heat expansion. It's an area where the turbo can benefit from the most flow possible if restrictions are removed. We have allowed this area to flow freely without obstruction and with enough piping diameter to allow the hot expanding exhaust gases to expell freely down the exhaust system. Way further downstream, where the large diameter piping is less critical due to reduced flow and reduced rated of expansion, the downpipe attaches the stock 2.5" exhaust system via an easy slip on clamp. We believe this simple but effective combination (3" catless downpipe and stock 2.5" exhaust) is great and perfect for taking the stock turbo to the max flow limit. We have dyno tested a full 3" turboback system over the 3" catless to 2.5"(stock exhaust) and there 3 - 4 additional peak HP to be made, but you run the risk of continually overspinning the turbo when boost is raised too high and there is potential for turbo damage. This is not to say that the full 3" turbo back system isn't a good idea for use on a larger than stock turbocharger on this engine.

High Flow Racing 3" downpipe assembly for K03/K04/GarrettMild350HP Turbos. Fits transversely mounted Quattro (AWD) 2.0L FSI equipped Audi A3 (2009 model tested), 304 stainless steel with gasketless/aircraft 3" stainless steel V-Band connection. Includes racing cat delete rear section (can be replaced with cat module later). Bolts directly to stock exhaust joint. All CNC mandrel bent and CNC flanges. TIG welded assembly. A must have mod for any "chipped" or "reflashed" vehicle to easily gain big HP and Torque. Over 30 ft/lbs and over 30WHP @ various parts of the power graph. V-Band system will be fully compatible with future V-Banded rear exhaust modules that will extend rear muffler and exhaust tips. Various "hot swappable" muffler, catalyst, and resonator options for power and sound tuning will be available to attach to this downpipe. All easy to install.