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      12-13-2012, 02:43 PM   #5
AWF30MSPORT
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Drives: '15 Porsche 981 Cayman GTS
Join Date: Mar 2012
Location: USA

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I have a manual transmission, and I only experience the overrun burble/pop when the car is Sport or Sport+. I have tested it under a wide range of conditions. I experience it at a standstill when revving the engine and letting off of the gas and also when I am in gear and engine braking. It is absolutely not there in Comfort or Eco mode. Overrun burble is excess unburnt fuel igniting in the exhaust system, so clearly fuel delivery is changing at some point to create the burble sound. No one seems to know if it's merely a superficial change to make it sound sportier to the driver during overrun, or if there are other changes to engine operation across the rev range in Sport/Sport+. Many people claim that the only difference between Comfort and Sport/Sport+ is a more sensitive and less linear throttle response, but I haven't seen or heard that claim substantiated. All I know is the car makes a pretty cool sound in Sport and Sport+ and the throttle response is a hell of a lot more fun.

Here are two videos demonstrating the differences between Comfort and Sport/Sport+ (just a disclaimer, neither of these are my videos, but my car sounds the same):

Comfort mode at the beginning, change to Sport+ at 50 second mark...




In this video, it starts out in Comfort, no burble, then at 1:07 you hear the exhaust flap servo, still in Comfort, and it sounds the same. Then at 1:25 you can hear the difference after switching to Sport mode...significant overrun burble sounds...


Last edited by AWF30MSPORT; 12-13-2012 at 04:49 PM.