A couple of days ago I installed the Toda Racing lightweight flywheel. It came as a kit with an Exedy Stg2 clutch disk and plate. I've been blamed in the past that I haven't provided any evidence about improvements on installed parts. Following is a before and after logging using my Ecutek cable and program:
Total gain is 0.34 sec or about 6%. The logging has been done on same road (w/o level differences), same external temperatures, same ignition timing etc.
PS: I have one more log and the accuracy is on the one hundredth of a second. So, I would say pretty accurate.