You don't want to do that to the springs. The do loose some of their mechanical properties over time but not that much. If you were to try and stretch them out it would severely deform them and they would not work correctly again. I.E. their spring rates and elastic properties would be shot. Either use them as they are or buy a new set.
1/4 11.28 @ 117mph
If its got Tits or Tires its going to be a problem