[Marky Mark]

Originally Posted by DuSh

I'm not 100% sure, but I think that is a so called "cold start" mode that ECU initiates on cold starts for a short duration (around 10 sec like you said). It opens up wastegates to bypass turbos and let catalytic converters warm up faster - only needed on cold start ups. basically in that scenario all gases go directly into exhaust through cats warming them up and as a consequence creating a growl that you hear. In normal mode wastegate is closed to allow gases go through the turbo and spin it up creating boost.
What I'm wondering tho, is if we can electronically open wastegates from time to time to experience that nice growl?

The exhaust has a valve on the right tailpipe. It opens when you first start "cold" engines because your car runs very rich when cold started.

The valve also opens when you hard accelerate over a certain rpm.

go over to the right tailpipe while the engine is running, you will see that nothing is coming out.

It can easily be coded to stay open, like stupid easy to code, but then you would lose some low end torque when accelerating. At lower RPM's the engine needs back pressure, at higher RPM's it needs less.

There are also noise laws which mandate that cars not be too loud when driving in town or idling. So the car's computer may not "open" the valve on the exhaust if you're sitting in your driveway revving the engine to see if it gets loud.