Exhausts with turbocharged engines are a bit of a compromise.
In terms of heat energy you want the turbo to be as close to the engine as possible to minimise losses, and that usually means simple log-style manifold.
But in terms of pressure recovery you want a good straight length after the collector to help smooth out the pressure pulses that the turbine section receives, again for best power & efficiency.
A well-designed set of extractors (header is the US terminology) must be very difficult in an aeroplanes engine cowling due to the lack of room available. So a simple log-style of manifold is often used and they work just fine for the application.