No idea mate on max safe drops. I was just reversing the suspension raise that the previous owner had done on my Sport. So I was only after the 1" drop all round that the Sport had. Getting the springs is a bit of a lottery, I got mine from Envy Performance (they should come up on google). Took longer to arrive than anticipated though. Might be worth PM'ing Monster Mat on here, as he may be able to get the same RS*R Down springs that I used a bit quicker. If I'm honest, I wouldn't want to slam my GS down by 3 inches, even the 1" drop gives me plenty of problems on driveways and speedbumps. With a car this long, it doesn't take much to ground the exhaust, I can't get my car down to the girlfriends garage at all. I think the 1" drop looks spot on with the wheels, albeit I have the 10" ones on the back.