I broke both my rear tailshafts under medium boost (16psi) while having a good solid crack at blasting up Arthur's Seat (essentailly a hill climb). I was coming out a 10km/h rated (for your ordinary sunday driver) corner, atleast that is what the sign said. Once my Aspec came onto boost, bang !!! And a whole bunch of front end wheel spin as well has a whole bunch of clunking from the rear end. 4 bolts are a worthy investment. LSD or no LSD. Just for added piece of mind that you have 4 bolts hold you together instead of 3...
Chris