The most obvious way you can tell a tuning job from a stock model is visual details, body modifications. The second most obvious way would be the awesome sounds you can get out of an aftermarket exhaust.
And exactly this is what we are going to hear when we play the video of a nice E90 BMW M3 going around the Sonoma raceway.

The soundtrack of the M3 comes from Macht Schnell Bypass Track Pipes using stock mufflers. The engine on the E90 Bimmer has also seen some improvement in the form of a VF620 supercharger. With this setup, the best results would have been on the track, so the Sonoma was a right choice.
In order to capture the experience in the E90 BMW M3, the owner asked EAS to install a special recording gadget. A camera was mounted on the vent beneath the driver’s side headlight, and a microphone was installed near the exhaust. All wires were hidden, and the setup made it easy to capture both video and sound without the need of syncing them later on.