Actually the packing you purchased was off 1.5 to 2 inches, let me share an experience, I first installed this packing on rear end of corolla07 . It looked hideous and breaking became worst, then I went back and had it removed. Took it for lathe shop and had him grinded both the packing equally till the time it reached half of its size and roughly near to half an inch. Had it re-installed and took the vehicle for back wheel alignment. Trust me, results were very good, car looked decent, braking improved to like it was before and no difference in comfort.
Why do people install packing ???? because CNG cylinder drops the back of car from its original height. It starts to hit the bump once loaded with passengers so basically we want the car to gain little bit of height and get compensated for CNG weight which has dropped the original height and yet not look hideous.