Porsche 991 Turbo Exhaust Development

Our 991 Turbo baseline dyno is complete and now it is time to mod and get some more power.  All of the design, fabricating, and testing is being completed here at our Arizona facility.  We have a handful of goals to obtain as we start the product development stage.  Because the car is so new and tuning is a issue, we want to make everything to be modular and CEL free.  With any turbocharged vehicle, the exhaust is a restriction.  There is a fine balance between performance and sound.  With the engineering Porsche has done in the new 991 including the economy mode, drone will be even more present than before.  If you are not in Sport Mode, the car can be running at 1500rpm as your cruising at 40mph down the road.  Previous 997 Turbo had a drone spot of around 2200-2800rpm.  So reducing backpressure to gain performance while keeping a clean sound for daily driving is priority 1.

Typically a X-Pipe design gives the car a bit of a muffled tone.  That is because of the turbulence where the X junction is.  Many people like this sound, however the turbulence can affect performance.  The only time we have heard a significant sound change is with a titanium exhaust (coming next) because of how the material resonates the sound.  We chose to do our system in a full 3 inch stainless steel as a U bend with dual resonators.  From the catalytic converter, the exhaust gas goes through 1 resonator, U turns through another resonator, and then out the exhaust tip.  This gives each turbo its own full 3″ outlet.  With the U-turn and 2 resonators, this should create a clean sound.  Utilizing this with the stock catalytic converters will give some increases over stock while keeping you emission clean and CEL free.  The exhaust is being designed to work with the factory tips as well as a custom exhaust tip we will be making.

In addition to the muffler setup, the 991 Turbo will receive some high flow cat pipes.  Like the 997.2 Turbo, the muffler and cats are separate allowing for a nice modular type system.  The Metal Core Catalytic Converters have been designed to provide a reliable solution to the most common converter problems experienced by other brands with out having an absorbanent cost.  They are considered a 300cell but as bench tested, flow more than the HJS 200 cell cat.  Each cat is full stainless steel construction, including the substrate which is furnace braised to the mantle for outstanding durability.  They feature a unique end-cap design so it can’t rattle around.  The GESI proprietary precious metal loading technology used in these catalytic converters ensures greatly reduced emissions, eliminating most “Check Engine Light” issues.  With the catalytic converters mounted straight to the turbos, these are capable of withstanding up to 1500F which is about the EGT temperature at full power.  The secondary O2 sensor mount will have a built in defowler bung for extra measures to prevent any CEL’s from coming on due to cat inefficiency.

Once the exhaust is finished, we will be working on a beautiful 3 into 1 header to replace the clam-sandwhich headers to help improve turbo spool and gain more power.  Each part that we make will be independantly tested and we will do some stock to fully modified PBox testing and 1/4 mile testing.  Enjoy the pictures and please comment away with input!

Porsche 991 Turbo Exhaust Development