Exhaust note when cold?

[Spooner]

Fitting a Milltek soon and don't want to upset the neighbours :-)

[M3R8]

You'll notice engine idle RPM is also higher during this time. I don't know why this is done though. It for sure deeply impresses anyone standing in the vicinity of the car when started

[Spooner]

Thanks for the reply...

[desperado]

The car is throwing in extra fuel to heat up the catalysts as rapidly as possible, for emissions purposes. Once the catalysts reach a temperature where they begin to be effective, the mixture returns to the correct setting. I seem to notice this warmup period increases when the temperatures are lower.

[M3R8]

Thanks for the explanation. And it sounds so **** good in the process...

[KfabR8]

So that's what's going on with the cold idle. Great info.

Its cold idle is just high enough that it makes my waste gates blow off just a tad and the car burbles and hisses, like a bag of angry snakes, for the first 10 seconds of morning life. It's pretty cool.

[tcoop1]

It's pretty cool.......no question, it carries on for a bit in these cold temps....
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[desperado]

And judging from the sound of it, not only is it putting in more fuel but I suspect it may be advancing the ignition timing or messing with the valve timing a little too(?), but I'm not sure what the engineering reason for that would be. Hence the brief period of sound like a 1960's muscle car.

[RS4Cab]

Find it even louder now with S/C. Had some people over for Xmas eve and was showing a friend my car in garage which is under house and he asked me to start it, car had not been started in about a week and it really made a booming sound. My wife said it scared the crap out of a couple people who thought a plane or something crashed outside the way the house shook