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Hi, went and saw an exhaust shop today- brief was 'release the farts!' but I didn't want any drone/thrumming when driving sedately. Without extensive full system re-works, the answer is a Varex system- factory quiet with the valves closed- straight through when fully open. When looking at the current factory setup I noticed that the outer exhaust outlet on each muffler is currently 'valved' with an actuator wired in- (see images)
**EDIT** A bit of googling revealed that an exhaust valve actuator (such as VW's) " Increased exhaust back pressure is used to elevate engine and engine coolant temperature faster. This can be especially helpful in very cold climates. This is a basic, generic overview of exhaust pack pressure valve operation. Check specifications for the vehicle in question before making any assumptions. When the PCM detects a cold air intake temperature that is below a minimum threshold, it will initiate exhaust back pressure valve operation and maintain it until the intake air temperature is normalized. Exhaust back pressure regulator activation usually only occurs once per each ignition cycle. The exhaust back pressure control valve is designed to park in the wide open position once it is deactivated by the PCM."
Leaves the question, will disconnecting these and fitting sports mufflers cause fault codes OR will fault codes only generate if the intake temperature registers the threshold temp required to activate the valves in an extreme-cold start situation (unlikely here in AUS)... I have an OBDeleven so I'll disconnect the cables from the actuators, do a start-cycle and see if any codes are generated...
**EDIT** A bit of googling revealed that an exhaust valve actuator (such as VW's) " Increased exhaust back pressure is used to elevate engine and engine coolant temperature faster. This can be especially helpful in very cold climates. This is a basic, generic overview of exhaust pack pressure valve operation. Check specifications for the vehicle in question before making any assumptions. When the PCM detects a cold air intake temperature that is below a minimum threshold, it will initiate exhaust back pressure valve operation and maintain it until the intake air temperature is normalized. Exhaust back pressure regulator activation usually only occurs once per each ignition cycle. The exhaust back pressure control valve is designed to park in the wide open position once it is deactivated by the PCM."
Leaves the question, will disconnecting these and fitting sports mufflers cause fault codes OR will fault codes only generate if the intake temperature registers the threshold temp required to activate the valves in an extreme-cold start situation (unlikely here in AUS)... I have an OBDeleven so I'll disconnect the cables from the actuators, do a start-cycle and see if any codes are generated...
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