While I cannot say with absolute certainty, I do not believe the stock "truck arms" are tempered steel, like spring. Most metals, certainly ferrous, have a degree of natural "springiness" to them and tend to return to their current shape when not bent too sharply. I have a set each of OEM GM, and Stock Car Products fabricated arms, and do not think either is made of more than a good grade of mild steel. However, shortening them will reduce distance over which the twist can be absorbed and result in a torsionally stiffer arm and if twisted enough, could result in taking a new "set" . I suppose it depends on how much shortening needs to be done. Two inches probably wouldn't matter much, but the greater the amount, the greater the negative effect.