Instead of dropping a fully sick burnout to test your diff, try jacking up the rear end and spinning one wheel (in neutral of course) if the other wheel spins in the same direction then it is an LSD
If I could afford one right now, id be buying one! I just reckon it would be good to get in on something that is supposed to be a limited edition. plus they look good and would only take a little tweaking to get that v8 roaring with your GT-P's