The seventh incarnation of the 911, the 991 turbo has taken some strikingly beautiful evolutionary steps. A wider wheel base, and improved axel to engine geometry significantly improve the weight distribution and cornering stability. additional composites and aluminium to further reduce weight, even the exhaust has been somewhat improved over the 997. So how much could we really improve over the factory exhaust? Quite simply remarkably!
Capitalising on the design innovations and success of our 996 and 997 range, the starting point for designing the 991turbo exhaust had been set high. Our trademark perfect x pipe geometry, harmonically tuned silencer geomtery, Inconel 625, and our proprietry acoustic silencer packing materials result in a system that has become famous for that perfect sound. Zero drone, and a raised pitch raucious incindiary howl in higher rpms and hard throttle. The design is so perfect, that you can even run catless versions silently at cruising speeds, only unleashing that howl when you drive the car hard.
During development there were some clear evolutionary design steps that we could incorporate. The secondary tail pipe allowed us to integrate an effective gas overflow system. The concept was conceived at the fluid dynamic modelling stage, and effectively works to cut low rpm noise, while allowing an effective increased cross section at higher rpms producing a more accentuated Jekyll and hyde personality, and slightly broader torque curves.
Available with decat pipes for optimum performance and sound, or with 100 or 200 cell HJS HDPE catalysts. The largest gain with decats is 38hp and 55nm. 100 cell and 200 cell catalysts produce 20hp, and 16hp respectively.
De-cat cross section 70mm OD specifically chosen for a balance of peak torque and power.
Silencer section, cross section 65mm OD and 44mm OD overflow
Catalysts come in a variety, from 108mm OD to 127mm OD
Turbo back system
Available in standard 304 grade stainless steel, weight 14kg 200cell cats, 12.5 with de-cat
Inconel 625 formula one grade material, weight 7.5kg
Titanium G2 silencer section is also available, weight comparable to Inconel
Standard 304 grade stainless, weight 6kg total
Inconel 625, weight, 2.9kg total
Titanium unable to endure extreme heat
Will be available soon in Aerospace grade carbon fiber