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By popular demand, HHR is pleased to offer our resonated secondary cat bypass for the 958 Cayenne. These resonated bypass pipes are available in 2.5" for the 958 Cayenne S-V8, GTS-V8, Turbo/Turbo S, and the new GTS-V6 Turbo models. They have become popular with our non-Turbo S-V8 and GTS-V8 customers who want the additional flow and performance of a secondary bypass, without the raspiness that may be experienced on the non-Turbo models.
The stock Porsche Cayenne has 2 sets of (4 total) catalytic converters and this bypass removes the rear set of cats (you will still have one full set remaining on the car) to increase HP/TQ, sound levels by a marginal amount and provide incremental weight savings. Similar in design to the standard secondary cat bypass, the resonated bypass differs by adding a resonator to the bypass. The resonator has a straight-through high-flow design, with a center perforated tube surrounded by packing to reduce the amplified metallic rasp that is generated from removing the stock cat.
We manufacture our own bypasses in Denver, Colorado. The tubing, flange, and 4 adjustable hangers are made from 304 stainless steel with a matte/brushed finish. We utilize a 2.5" tube which mates up to the factory down pipe, then to the factory exhaust. Our flanges are 3/8 inch 304 stainless steel, CAD-designed to match factory specs and precision water jet cut. Our bypass pipes also incorporate four unique, independently-adjustable stainless hangers for easier fitment and to allow customers to adjust their bypass clearance as the exhaust moves over time. In addition, we have realized the importance of the hangers in supporting the midsection of the exhaust. While the bypasses are considerably lighter than the factory cats, hangers are mandatory because the factory downpipes are flexible braided stainless steel and are not designed to be weight bearing. Adding bypasses without hangers will eventually damage the factory downpipes.
Bypass pipes will provide a power increase and on the Turbo models will allow the turbos to spool significantly quicker. This product will provide significant power peak gains after an ECU tune although a custom tune is not required to achieve power gains; it is a noticeable difference and you will feel the difference the first time you drive with them installed. On the Cayenne S, the bypass provides immediate add-on power gains throughout the power band with peak gains of 15hp to 17hp.
We believe this is a DIY project for anyone capable of operating a wrench. We provide detailed instructions, needed hardware and aluminum gaskets. This project is estimated at 120 minutes. Plan for us to ship your pipes 3 days after cleared payment. As usual, feel free to email or call with any questions. Thank you! -Hank