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Headers & Exhaust

The headers turned out to be quite an undertaking.  Due to the shape of the engine bay and specifically the way the firewall is shaped, a set of custom headers had to be crafted.  They are made up of sections of stainless tubing carefully cut and shaped to the appropriate dimensions.  All joints were TIG welded and this task alone took quite a considerable amount of time.

On each bank, three tubes corresponding to each cylinder dump into a collector midway.  At the top of the collection point is a welded "bung" used to house the oxygen sensors.  Mounting the O₂ sensors as close to the head as possible enable them to become fully operational in a short amount of time.  This helps to get the engine running in closed-loop quicker.

Exhaust System

The headers are connected on either side to a pair of intermediary stainless tubes.  These tubes are shaped to bend around in such a way to allow air flow and prevent the passenger cabin (mainly where your feet go) from getting hot.  Both the headers as well as the intermediary pipes are JetHot ceramic coated, again in an attempt to control heat radiation.

Behind the intermediary pipes, a pair of Glasspack mufflers are welded in place.  They are located approximately in the middle of the car and are tucked into the T-shirt area of the frame.  At that point they flare out and are capped with a pair of Supertrapp adjustable diffusers.

The Supertrapp diffusers are pretty neat, because they can be adjusted for sound and performance.  This is done by adding or removing discs in the diffuser assembly.  By adding more discs, the sound level goes up and backpressure is reduced.  By removing discs, sound levels go down and backpressure is increased.  After a few combinations, a happy median was found.  The exhaust note is quite aggressive especially in WOT conditions, but at speed in fifth gear it is quite acceptable.  Plus the Supertrapps have a unique and special sound to themselves.

Having a set of exhaust pipes sticking out from the rear valance is not my idea of cool.  So, the diffusers are tucked in neatly just past the differential.  This gives a stealth quality to the exhaust system.