EXHAUSTS THE ART OF FINE TUNING

Defining and creating Porsche exhaust notes requires its own department. Total 911 looks at the evolution of flat six sounds Written

- Kieron Fennelly

For the enthusiast, a car is defined among other features by its exhaust note. TVR is one of the best examples of this. Historically, the mass manufacturers fitted the cheapest mild steel pipes they could obtain. This gave rise to a huge aftermarket for companies such as Peco or Speedwell, which sold chromed tailpipes and largerbore stainless steel componentry in their hundreds of thousands to car owners seeking more noise and (often misguidedly) performance.

At Porsche, things were slightly different. The rear engine meant the exhaust was much shorter and more convoluted, and the 911’s exhaust, like the rest of the car, was properly engineered to duct away waste gases without compromising performance. Few Porsche fans complained that 1970s or 1980s 911s weren’t loud enough! Indeed, the apogée of 911 acoustics was probably the 964, whose barrelchested baritone rumble remains one of the great Porsche sounds.

However, that began to change with the 993. The twin outlet setup – one exhaust per bank of cylinders, effectively dividing the beat of the flat six – muted the sound effects. Louder aftermarket pipes for the 993 soon appeared, but in terms of efficiency the standard system was said to be impossible to better. By the 1990s Porsche was also confronted with drive-by noise regulations, which were especially hard on the air-cooled 911, where engine and exhaust noise is concentrated at the rear. Indeed, for decibel reasons, the Swiss and Austrian versions were fitted with the higher ratio G50/20 gearbox of US-specified cars.