I'm setting up a new 12 bolt, and just have to pick the gear set. I have a set of 4:88's available (and a spacer) that I now own. My two ton Cutlass has a 650 hp 439 in it, and it maxes out at 7200 rpm. 4:56's would lower my rpm's through the trap to about 6400 with a 30" tire. 4:88's go to 6900 rpm. I know it's crazy, but I was thinking of saving the valve springs on the car, not to mention the rest of the engine. Any opinions? Too bad it's not a torque monster, or I could maybe go lower, 4:33's or something.