The development of the split downpipe for the S4 started with a prototype open-mouth downpipe. After producing and installing several of these pipes, LaBree Motorsports initially formulated a hypothesis that it would be easier from a fabrication standpoint to create a split downpipe version of the Audi S4 downpipe. LaBree contacted Tantrumwerks to obtain an OEM K03 turbo and the new fabrication process began.

There are three main components that are exclusive to this downpipe design: (1) Downpipe Flange (2) Wastegate Separator (3) Split pipe size & shape. LaBree Motorsports managed to find a way to make all three work in harmony to produce a downpipe with the same overall diameter that produces more horsepower than current open-mouth designs. All of these components are proprietary in nature.

The downpipe flange that bolts up to the turbo only allows space for the split pipes and wastegate separator. There is no wasted space in this area for additional turbulence that occurs in open-mouth designs where the exhaust flow is merged immediately. The wastegate separator bolts to the down pipe at the flange and fits in the turbo exhaust housing creating a perfect circle for the exhaust to exit like an external wastegate turbo. The split pipes themselves have been mandrel-bent to the most efficient radius possible to maintain high velocity exhaust flow.

All downpipes are now made by Fast Intentions and test fitted on a K03 turbo before shipment. The split portion of the downpipes are made with 16-gauge, T-304 stainless steel. The “merged” portion of the pipe can be constructed of 14-gauge stainless steel or 14-gauge aluminized steel. The aluminized option (if chosen) is then coated with high-temperature ceramic coating for protective and heat management purposes. Aluminized material also provides a cost savings to those customers who wish to pursue that option. The welds on the flanges are MIG on the inside of the pipes, which are then ported & polished. The only exceptions are the welds at the flex joint & the “merged” portion of the downpipe, which are TIG welds. The flex joint is also constructed of stainless steel.

Our downpipes have proper O2 sensor placement with fittings just after the turbo and after the catalytic converter. These downpipes will work with stock programming or aftermarket programming without throwing DTC’s or CEL’s. Catalytic converters are 300-cell metallic hi-flow configuration. With the cats installed, you should pass an emissions test if one is conducted on your vehicle at proper operating temperature. To prove this point, we have included results from a California smog test performed on our 6-speed test car along with our dyno charts.

Our downpipes have been running on hundreds of vehicles for over 7 years now. Most of these cars are daily drivers and 2 of the vehicles have seen track time during their initial testing phase. Both of the cars that produced dyno results have over 40 dyno pulls each on them in before and after testing.