I did a similar test with my Porsche 997 turbo. Here are the results from the Racelogic Performance Box.
1 mod: Europipe exhaust

Testmethod: dumping the clutch at 3K RPM.

0-100kph (0-62mph): 3,72 seconds (best time)
0-100kph (0-62mph): 3,91 seconds (average)
0-100kph (0-62mph): 4,63 seconds (worst time -> normal launch without dumping the clutch at 3K rpm)

0-160kph (0-100mph): 8,00 seconds (best time)
0-160kph (0-100mph): 8,32 seconds (average)

0-200kph (0-124mph): 12,38 seconds (best time)

Quarter mile (402m): 11,90 seconds (best time) speed: 195,50kph (121,48mph)


3 videos:

0-100kph launch
YouTube: http://www.youtube.com/watch?v=1XqHYIBUwEg
Soapbox MSN: http://video.msn.com/video.aspx?vid=9ce77f10-8217-47c2-8acf-27668417ab90

0-100kph launch (2)
YouTube: http://www.youtube.com/watch?v=omtEnSszlrA
Soapbox MSN: http://video.msn.com/video.aspx?vid=c1709249-a9ff-477d-a054-e802319f4bbf

Fly-by
YouTube: http://www.youtube.com/watch?v=t0S5Yx4Ldz0
Soapbox MSN: http://video.msn.com/video.aspx?vid=9d837b06-0c1e-41e2-a7fb-de2950f9ca7c

As you can see on the videos there is a lot less drama compared to my Gallardo ... but the Porsche is clearly faster