Yes, please dont do that. That is so ghetto. It will ruin your handling. Nowadays you can buy some decent springs for like $140 shipped or less, why would you cut your springs.
Ok, that is not entirely true. If you cut them TOO short it will fuck a lot of things up. However, as far as destroying handling...cutting springs can help A TON! There is a 1995 Mustang 5.0 that runs AutoX here in Idaho. With his stock springs he handled like shit...TONS ofd body roll. Then he cut the springs on that and it fixed nearly ALL of his handling problems. In reality, it is a pretty good idea in some scenarios. You keep the same spring rate, but you have shorter springs. In my opinion it is FAR better than heating and compressing.