I was layin down doin a race at the test course so I decided to put it on my stomache and rest and just hokd X...after my 40 lap race was done I felt like I did 234576 sit ups.
I don't know if I'm the only one who's experienced this, but after using the Dual Shock, I've gotten used to it. I don't notice the vibrations anymore. Kinda weird. But I do notice if the vibration is turned off. Anyone else do this too??