I could have sworn that I heard my car make the valve clack noise the other day, but I just did a recording (with a good quality 25mm diaphragm condenser mic) and didn't hear it at all. I figured I'd provide the recording for you guys, so you have a point of reference (a baseline, really) for an M3 startup
without the sound. Just in case anyone tries to tell you "it's perfectly normal".
The MP3 file is compressed at 192 kbps fixed bitrate, but I only have the (pretty crappy) LAME MP3 encoder, so I provided uncompressed formats if someone needs to do in-depth analysis. The WAV file should play on just about anything. The FLAC file is a "lossless" compressed format.
2013 M3 Startup MP3 format (433 KB)
2013 M3 Startup WAV format (1.6 MB)
2013 M3 Startup FLAC format (1.2 MB)