heheh... It depends on whether or not the weight is rotating mass. I'm not sure there's even 50lbs spinning in a civic drivetrain, though.

I swapped the 42lb stock wheels for 18 lb wheels on my GSX and shaved 100lbs off it. It made a huge difference, but that's all rotating mass. I doubt you could pull off a full 1/10th of a second from losing 50 lbs of dead weight.